Aug 26 - Update password detect against off field 2

CLAUDE.md

@@ -53,6 +53,7 @@ passkeeper/
 │   │   ├── emergency_access.py      # State machine
 │   │   ├── recovery_challenge.py    # Server-side recovery challenge (multi-worker safe)
 │   │   ├── webauthn_credential.py   # Passkey / WebAuthn credentials (one row per key)
+│   │   ├── login_attempt.py         # Failed-login lockout scoped to (user, IP)
 │   │   └── audit_log.py
 │   ├── routes/
 │   │   ├── auth.py          # Register, login, MFA, logout, refresh, change-password, recovery
@@ -120,6 +121,7 @@ passkeeper/
 │   ├── test_sharing_expiry.py       # expires_days fails closed
 │   ├── test_registration_privacy.py # register does not disclose account existence
 │   ├── test_emergency_visibility.py # grantor sees requests + retrievals
+│   ├── test_login_lockout.py       # per-IP lockout; no disclosure, no DoS
 │   ├── test_deploy_config.py        # nginx/gunicorn/systemd/extension packaging guards
 │   └── js/
 │       ├── test_psl.js              # PSL same-site matching (node, run in CI)
@@ -249,6 +251,7 @@ CREATE TABLE webauthn_credentials (
 | `j0k1l2m3n4o5`   | Add recovery_verifier (decouple recovery proof)  |
 | `k1l2m3n4o5p6`   | Add token_epoch (revoke sessions on pw change)   |
 | `l2m3n4o5p6q7`   | Add emergency vault retrieval tracking           |
+| `m3n4o5p6q7r8`   | Add login_attempts (per-IP lockout)              |
 
 ---
 
@@ -261,6 +264,13 @@ CREATE TABLE webauthn_credentials (
 - **Item name:** `enc_name`/`iv_name` in `vault_items`; server `name` column = item type only
 - **Shared item name:** `enc_name`/`iv_name` encrypted with ECDH shared key; server `item_name` = item type only
 - **Tags:** `plain.tags: string[]` inside `enc_data`; server never sees them
+- **Login lockout:** scoped to (account, source IP) in `login_attempts`, NOT
+  global. A global counter made it a DoS primitive — anyone knowing an address
+  could lock the real owner out for 15 minutes, repeatedly. Every failure mode
+  (unknown account / wrong password / locked out) returns one identical 401 with
+  matching timing, so it discloses nothing. `users.failed_login_count` and
+  `locked_until` remain as an aggregate audit signal only; they no longer gate
+  authentication.
 - **Argon2id:** double-hashes `authHash` server-side; transparently rehashes on login if parameters are upgraded
 - **JWT:** HS256, 15 min access / 7 day refresh, JTI blacklisted on logout.
   Every token carries an `epoch` claim checked against `users.token_epoch`;
@@ -647,6 +657,35 @@ is ever dispatched and the save-credentials banner never appeared.
 
 `_captureCooldown` (2 s) prevents two triggers double-prompting for one login.
 
+### Insecure-page warning
+
+The extension keeps `http://*/*` permission deliberately: routers, NAS boxes,
+printers and self-hosted panels are often reachable only over plain HTTP on the
+LAN, and those are exactly the devices whose passwords get reused.
+
+`_isTrustworthyOrigin()` classifies the page. HTTPS, `file:`, `localhost`,
+reserved TLDs (`.local` / `.lan` / `.home` / `.internal`) and RFC1918 /
+loopback / link-local / RFC4193 addresses are accepted silently. Any other
+`http://` origin gets a red warning row prepended to the suggestion dropdown.
+
+**IPv4 checks must match in FULL** (`$`-anchored). A prefix test like
+`hostname.startsWith("127.")` also accepts the registrable
+`127.0.0.1.evil.com`, which would silently suppress the warning on a hostile
+site. Guarded by `tests/js/test_field_heuristics.js`.
+
+Filling is never automatic, so this warns rather than blocks — silently
+offering nothing would just look like a broken extension.
+
+### Autologin without a `<form>`
+
+`_findSubmitControl(pwField)` locates the control that submits the login,
+walking up to 5 ancestors when there is no `<form>`. It skips invisible
+elements, wrappers containing other inputs, labels over 40 chars, and anything
+matching `_NEGATIVE_CONTROL` (cancel / reset / back / forgot / register / sign
+up), then clicks it — `form.submit()` is only the last resort because it
+bypasses site handlers entirely. Returns null when nothing is convincing;
+leaving a filled form for the user beats clicking the wrong thing.
+
 ### MutationObserver guard
 
 Inspects added/removed nodes — if all carry `__pk` prefix, returns early. Prevents re-decoration loops when the extension injects/removes its own UI.
@@ -682,7 +721,7 @@ Audit log details **never** contain plaintext item names, shared item names, or
 - `#vault-list` ID must not be renamed — `vault.js` renders into it directly
 - `_validate_folder_id` must be called for any user-supplied `folder_id` before DB write
 - `verify_auth_token` must receive `user=user` at both `login` and `change_password` to enable Argon2 rehash
-- APScheduler cleanup job handles `TokenBlacklist`, `RecoveryChallenge`, AND `TotpUsedCode`; guard with `os.environ.get('WERKZEUG_RUN_MAIN') == 'true'` in Flask debug mode to prevent double-start
+- APScheduler cleanup job handles `TokenBlacklist`, `RecoveryChallenge`, `TotpUsedCode`, expired shares AND `LoginAttempt`; guard with `os.environ.get('WERKZEUG_RUN_MAIN') == 'true'` in Flask debug mode to prevent double-start
 - `password_changed_at` lives inside `plain` (encrypted) — never in the server schema
 - WebAuthn `attachment`: `"cross-platform"` for security keys; `"platform"` for device biometrics (default)
 - `enc_vault_is_legacy` check in `EmergencyAccess.to_dict()` is pure JSON inspection — no decryption
@@ -690,6 +729,9 @@ Audit log details **never** contain plaintext item names, shared item names, or
 - `/register` must return the SAME body and status for new and existing addresses, and hash on both paths — returning early on duplicate reinstates a timing oracle
 - Never return `str(e)` from exception handlers — log with `_log.exception(...)` and return a generic user-facing message to avoid leaking DB schema details or query fragments
 - `extension/shared/psl.js` is GENERATED — never hand-edit; run `python scripts/update_psl.py`. It must load BEFORE content.js / popup.js / background.js in every manifest
+- Host/IP allowlists must be `$`-anchored — `startsWith("127.")` also matches the attacker-registrable `127.0.0.1.evil.com`
+- `escHtml` must escape `&`, `<`, `>`, `"` AND `'` in all three copies (vault.js, popup.js, content.js) — templates mix quote styles
+- Login lockout lives in `login_attempts` keyed by (user, IP); never move it back to a global per-account counter
 - Never add `off` back to `NON_CRED_AC` in `content.js` — `tests/js/test_field_heuristics.js` fails the build if you do
 - Login detection must not assume a `<form>` exists; route new capture triggers through `maybeCaptureCredentials()`
 - Never reintroduce `endsWith("." + host)` host matching anywhere in the extension — `tests/test_deploy_config.py` fails the build if it reappears
@@ -711,7 +753,7 @@ Audit log details **never** contain plaintext item names, shared item names, or
 | `auth.py`      | `auth.register`                                        | New account                    |
 | `auth.py`      | `auth.register_duplicate`                              | Register attempt on an existing address (no email in detail) |
 | `auth.py`      | `auth.login` / `auth.login_failed`                     | Login success/fail             |
-| `auth.py`      | `auth.account_locked`                                  | Failed login lockout           |
+| `auth.py`      | `auth.account_locked` / `auth.login_blocked`           | Per-IP lockout triggered / hit |
 | `auth.py`      | `auth.mfa_enable/disable/verify`                       | TOTP actions                   |
 | `auth.py`      | `auth.mfa_backup_code_used`                            | Backup code login              |
 | `auth.py`      | `auth.mfa_backup_codes_regenerated`                    | Backup code regen              |
@@ -908,8 +950,12 @@ Features planned for future implementation. Ordered by priority within each cate
 - Share `expires_days` fails closed instead of silently meaning "never"
 - nginx `api_limit` corrected from 60r/m to 10r/s
 - Registration no longer discloses account existence (status, body and timing)
+- Login lockout scoped per-IP: no account disclosure, no lock-out-the-owner DoS
+- `escHtml` escapes single quotes; dead `User.check_password` removed
+- Extension warns before filling on plaintext public pages; autologin works
+  without a `<form>`
 - Emergency access: requests and vault retrievals are now visible to the grantor
-- pytest suite (66 tests) + PSL node test + CI jobs; `gunicorn.conf.py`;
+- pytest suite (77 tests) + 2 node test files + CI jobs; `gunicorn.conf.py`;
   systemd watchdog removed
 
 ### High priority — user-facing

app/__init__.py

@@ -114,6 +114,7 @@ def create_app(config_name: str = 'development') -> Flask:
     from .models.recovery_challenge import RecoveryChallenge
     from .models.totp_used_code import TotpUsedCode
     from .models.webauthn_credential import WebAuthnCredential
+    from .models.login_attempt import LoginAttempt
 
     @login_manager.user_loader
     def load_user(user_id):
@@ -204,9 +205,11 @@ def create_app(config_name: str = 'development') -> Flask:
                     from app.models.recovery_challenge import RecoveryChallenge
                     from app.models.totp_used_code import TotpUsedCode
                     from app.models.shared_item import SharedItem
+                    from app.models.login_attempt import LoginAttempt
                     TokenBlacklist.cleanup_expired()
                     RecoveryChallenge.cleanup_expired()
                     TotpUsedCode.cleanup_expired()
+                    LoginAttempt.cleanup_expired()
                     # Delete expired unaccepted shares.
                     from datetime import datetime, timezone
                     SharedItem.query.filter(

app/models/login_attempt.py

@@ -0,0 +1,112 @@
+from datetime import datetime, timedelta, timezone
+
+from sqlalchemy.dialects.mysql import INTEGER
+
+from app import db
+
+
+class LoginAttempt(db.Model):
+    """
+    Failed-login tracking scoped to (account, source IP).
+
+    The lockout used to live on the users table as a single global counter, which
+    made it a denial-of-service primitive: anyone who knew an address could send
+    five wrong passwords and lock the real owner out for 15 minutes, repeatedly
+    and indefinitely. Locking someone out of their password manager is a serious
+    harm on its own — it can mean losing access to everything at the worst
+    possible moment — and it cost an attacker almost nothing.
+
+    Scoping by IP means an attacker locks out only themselves. The victim signing
+    in from their own address is unaffected. A distributed attacker has to rotate
+    IPs, and each one is independently capped by Flask-Limiter (10/min on
+    /login) plus the Nginx auth_limit zone.
+
+    users.failed_login_count / users.locked_until still exist and are still
+    maintained, but ONLY as an aggregate signal for the audit log and security
+    dashboard. They no longer gate authentication — enforcement is here.
+    """
+    __tablename__ = 'login_attempts'
+
+    id = db.Column(INTEGER(unsigned=True), autoincrement=True, primary_key=True)
+    user_id = db.Column(
+        INTEGER(unsigned=True),
+        db.ForeignKey('users.id', ondelete='CASCADE'),
+        nullable=False,
+    )
+    # 45 chars covers IPv6; may be empty when the proxy supplies no address.
+    ip_address = db.Column(db.String(45), nullable=False, default='')
+    failed_count = db.Column(db.Integer, nullable=False, default=0, server_default='0')
+    locked_until = db.Column(db.DateTime, nullable=True)
+    updated_at = db.Column(
+        db.DateTime,
+        nullable=False,
+        default=lambda: datetime.now(timezone.utc).replace(tzinfo=None),
+    )
+
+    __table_args__ = (
+        db.UniqueConstraint('user_id', 'ip_address', name='uq_login_attempt_user_ip'),
+    )
+
+    MAX_FAILED = 5
+    LOCKOUT_MINUTES = 15
+    # Rows older than this carry no information and are pruned by the scheduler.
+    RETENTION_HOURS = 24
+
+    @staticmethod
+    def _now():
+        return datetime.now(timezone.utc).replace(tzinfo=None)
+
+    @classmethod
+    def get(cls, user_id: int, ip_address: str):
+        return cls.query.filter_by(
+            user_id=user_id, ip_address=ip_address or ''
+        ).first()
+
+    @classmethod
+    def is_locked(cls, user_id: int, ip_address: str) -> bool:
+        """True if this IP is currently locked out of this account."""
+        row = cls.get(user_id, ip_address)
+        if not row or not row.locked_until:
+            return False
+        if row.locked_until > cls._now():
+            return True
+        # Expired — reset so the next failure starts a fresh count.
+        row.failed_count = 0
+        row.locked_until = None
+        row.updated_at = cls._now()
+        return False
+
+    @classmethod
+    def record_failure(cls, user_id: int, ip_address: str) -> bool:
+        """
+        Count a failed attempt. Returns True if this attempt triggered a lockout.
+        Caller commits.
+        """
+        now = cls._now()
+        row = cls.get(user_id, ip_address)
+        if row is None:
+            row = cls(user_id=user_id, ip_address=ip_address or '', failed_count=0)
+            db.session.add(row)
+
+        row.failed_count = (row.failed_count or 0) + 1
+        row.updated_at = now
+        if row.failed_count >= cls.MAX_FAILED:
+            row.locked_until = now + timedelta(minutes=cls.LOCKOUT_MINUTES)
+            return True
+        return False
+
+    @classmethod
+    def clear(cls, user_id: int, ip_address: str) -> None:
+        """Successful authentication — drop this IP's failure history."""
+        row = cls.get(user_id, ip_address)
+        if row is not None:
+            db.session.delete(row)
+
+    @classmethod
+    def cleanup_expired(cls) -> int:
+        """Delete rows untouched for RETENTION_HOURS. Called by the scheduler."""
+        cutoff = cls._now() - timedelta(hours=cls.RETENTION_HOURS)
+        return cls.query.filter(cls.updated_at <= cutoff).delete()
+
+    def __repr__(self):
+        return f'<LoginAttempt user={self.user_id} ip={self.ip_address} n={self.failed_count}>'

app/models/user.py

@@ -1,7 +1,5 @@
 from datetime import datetime, timezone
 from flask_login import UserMixin
-from argon2 import PasswordHasher
-from argon2.exceptions import VerifyMismatchError, VerificationError, InvalidHashError
 from sqlalchemy.dialects.mysql import INTEGER
 
 from app import db
@@ -70,12 +68,14 @@ class User(db.Model, UserMixin):
     folders = db.relationship('Folder', backref='owner', lazy='dynamic', cascade='all, delete-orphan')
     vault_items = db.relationship('VaultItem', backref='owner', lazy='dynamic', cascade='all, delete-orphan')
 
-    def check_password(self, auth_hash: str) -> bool:
-        ph = PasswordHasher()
-        try:
-            return ph.verify(self.master_hash, auth_hash)
-        except (VerifyMismatchError, VerificationError, InvalidHashError):
-            return False
+    # NOTE: there is intentionally no check_password() here.
+    #
+    # It existed, was called from nowhere, and used default Argon2 parameters
+    # with no rehash-on-login handling — so any caller that found it would have
+    # silently bypassed the transparent parameter upgrade in
+    # auth_service.verify_auth_token(). Verification goes through
+    # verify_auth_token(auth_hash, user.master_hash, user=user) so the stored
+    # hash is upgraded when ARGON2_* settings change.
 
     def __repr__(self):
         return f'<User {self.email}>'

app/models/vault_item.py

@@ -23,9 +23,11 @@ class VaultItem(db.Model):
     user_id = db.Column(INTEGER(unsigned=True), db.ForeignKey('users.id', ondelete='CASCADE'), nullable=False)
     folder_id = db.Column(INTEGER(unsigned=True), db.ForeignKey('folders.id', ondelete='SET NULL'), nullable=True)
     item_type = db.Column(db.String(20), nullable=False, default=ItemType.PASSWORD.value)
-    # name is stored in plaintext for display in the vault list.
-    # All other sensitive fields (username, password, URL, notes, etc.)
-    # are inside enc_data and are encrypted client-side with AES-256-GCM.
+    # NOT the user-visible name — that lives encrypted in enc_name/iv_name below.
+    # This column holds the item TYPE string only (the same value as item_type),
+    # kept because the column is NOT NULL and predates enc_name. Writing a real
+    # item name here would hand the server plaintext the zero-knowledge model
+    # promises it never sees.
     name = db.Column(db.String(255), nullable=False)
     enc_data = db.Column(db.Text, nullable=False)   # base64-encoded AES-256-GCM ciphertext
     iv = db.Column(db.String(64), nullable=False)   # base64-encoded 12-byte GCM nonce

app/routes/auth.py

@@ -209,12 +209,9 @@ def register():
 @auth_bp.route('/login', methods=['POST'])
 @limiter.limit('10 per minute')
 def login():
-    from datetime import datetime, timezone, timedelta
-    from sqlalchemy.exc import OperationalError
-
-    # Number of consecutive failures before a temporary lockout is applied.
-    MAX_FAILED_LOGINS = 5
-    LOCKOUT_MINUTES = 15
+    from datetime import datetime, timezone
+    from sqlalchemy.exc import OperationalError, ProgrammingError
+    from app.models.login_attempt import LoginAttempt
 
     data = request.get_json(silent=True) or {}
     email = (data.get('email') or '').strip().lower()
@@ -225,73 +222,91 @@ def login():
     if not email or not auth_hash:
         return jsonify({'error': 'Email and auth_hash are required'}), 400
 
+    # ── One response for every failure mode ─────────────────────────────────
+    #
+    # Unknown account, wrong password, and locked-out must be indistinguishable.
+    # The lockout branch used to answer 429 "Account temporarily locked. Try
+    # again in N minute(s)", which confirmed the address had an account — the
+    # same disclosure /register was just fixed for.
+    #
+    # The trailing hint is shown for ALL of these, so it explains a lockout to
+    # the legitimate owner without revealing anything to someone probing.
+    def _reject():
+        return jsonify({
+            'error': (
+                'Invalid email or password. If you have made several failed '
+                'attempts, wait a few minutes and try again.'
+            )
+        }), 401
+
+    ip = client_ip()
     user = User.query.filter_by(email=email).first()
 
-    # Per-account lockout check.
-    # Guarded with try/except so that a deployment where the migration has not
-    # yet been run (columns missing) degrades gracefully instead of returning
-    # an HTML 500 page that breaks JSON parsing in the extension.
+    # Lockout is scoped to (account, IP) — see app/models/login_attempt.py.
+    # Guarded so a deployment where the migration has not yet run degrades to
+    # "no lockout" rather than returning an HTML 500 that breaks JSON parsing
+    # in the extension.
+    locked = False
+    if user:
         try:
-        if user and user.locked_until:
-            now = datetime.now(timezone.utc).replace(tzinfo=None)
-            if user.locked_until > now:
-                remaining = int((user.locked_until - now).total_seconds() // 60) + 1
+            locked = LoginAttempt.is_locked(user.id, ip)
+            db.session.commit()
+        except (OperationalError, ProgrammingError):
+            db.session.rollback()  # table missing — migration pending
+
+    if locked:
+        # Do the Argon2 work anyway. Returning early would make the locked
+        # branch measurably faster than a wrong password and reinstate the
+        # existence oracle through timing.
+        verify_auth_token(auth_hash, user.master_hash)
         AuditLog.log(
             user_id=user.id,
             action='auth.login_blocked',
             resource_type='user',
             resource_id=user.id,
-                    detail=f'Login blocked — account locked for {remaining} more minute(s)',
-                    ip_address=client_ip(),
+            detail='Login blocked — this IP is temporarily locked out',
+            ip_address=ip,
         )
         db.session.commit()
-                return jsonify({
-                    'error': f'Account temporarily locked. Try again in {remaining} minute(s).'
-                }), 429
-            else:
-                # Lockout has expired — reset the counter.
-                user.failed_login_count = 0
-                user.locked_until = None
-    except OperationalError:
-        # Columns do not exist yet — migration pending. Skip lockout check.
-        db.session.rollback()
+        return _reject()
 
     if not user or not verify_auth_token(auth_hash, user.master_hash, user=user):
         if user:
             try:
-                user.failed_login_count = (user.failed_login_count or 0) + 1
-                if user.failed_login_count >= MAX_FAILED_LOGINS:
-                    user.locked_until = datetime.now(timezone.utc).replace(tzinfo=None) + timedelta(minutes=LOCKOUT_MINUTES)
-                    AuditLog.log(
-                        user_id=user.id,
-                        action='auth.account_locked',
-                        resource_type='user',
-                        resource_id=user.id,
-                        detail=f'Account locked for {LOCKOUT_MINUTES} minutes after {user.failed_login_count} failed attempts',
-                        ip_address=client_ip(),
-                    )
-                else:
-                    AuditLog.log(
-                        user_id=user.id,
-                        action='auth.login_failed',
-                        resource_type='user',
-                        resource_id=user.id,
-                        detail=f'Failed login attempt — invalid password ({user.failed_login_count}/{MAX_FAILED_LOGINS})',
-                        ip_address=client_ip(),
-                    )
-                db.session.commit()
-            except OperationalError:
+                triggered = LoginAttempt.record_failure(user.id, ip)
+            except (OperationalError, ProgrammingError):
                 db.session.rollback()
+                triggered = False
+
+            # users.failed_login_count / locked_until are kept up to date purely
+            # as an aggregate signal for the audit log and security dashboard.
+            # They no longer gate authentication.
+            try:
+                user.failed_login_count = (user.failed_login_count or 0) + 1
+            except (OperationalError, ProgrammingError):
+                db.session.rollback()
+
             AuditLog.log(
                 user_id=user.id,
-                    action='auth.login_failed',
+                action='auth.account_locked' if triggered else 'auth.login_failed',
                 resource_type='user',
                 resource_id=user.id,
-                    detail='Failed login attempt — invalid password',
-                    ip_address=client_ip(),
+                detail=(
+                    f'This IP locked out for {LoginAttempt.LOCKOUT_MINUTES} minutes '
+                    f'after {LoginAttempt.MAX_FAILED} failed attempts'
+                    if triggered else
+                    'Failed login attempt — invalid password'
+                ),
+                ip_address=ip,
             )
             db.session.commit()
-        return jsonify({'error': 'Invalid email or password'}), 401
+        return _reject()
+
+    # Successful authentication — clear this IP's failure history.
+    try:
+        LoginAttempt.clear(user.id, ip)
+    except (OperationalError, ProgrammingError):
+        db.session.rollback()
 
     # Successful authentication — reset lockout state.
     try:

app/static/js/vault.js

@@ -4640,11 +4640,15 @@ const Vault = (() => {
   }
 
   function escHtml(str) {
-    return String(str)
+    // " and ' are both required: templates in this file use a mix
+    // of double- and single-quoted attributes, and an unescaped quote of
+    // either kind lets injected text break out of an attribute.
+    return String(str ?? "")
       .replace(/&/g, "&")
       .replace(/</g, "&lt;")
       .replace(/>/g, "&gt;")
-      .replace(/"/g, "&quot;");
+      .replace(/"/g, "&quot;")
+      .replace(/'/g, "&#39;");
   }
 
   function itemIcon(type) {

extension/content/content.js

@@ -32,10 +32,17 @@
   // ── Helpers ──────────────────────────────────────────────────────────────────
 
   function escHtml(str) {
+    // " and ' are both required: templates in this file use a mix
+    // of double- and single-quoted attributes, and an unescaped quote of
+    // either kind lets injected text break out of an attribute.
+    // This copy previously escaped neither, while injecting attacker-influenced
+    // values (site hostname, stored item names) into attributes.
     return String(str ?? "")
       .replace(/&/g, "&")
       .replace(/</g, "&lt;")
-      .replace(/>/g, "&gt;");
+      .replace(/>/g, "&gt;")
+      .replace(/"/g, "&quot;")
+      .replace(/'/g, "&#39;");
   }
 
   /**
@@ -74,6 +81,69 @@
     };
   }
 
+  /**
+   * True when this page is safe enough to put a stored credential into.
+   *
+   * The extension holds http://*\/* permission on purpose: a great many devices
+   * that genuinely need a password manager — routers, NAS boxes, printers,
+   * self-hosted admin panels — are only reachable over plain HTTP on the local
+   * network, and dropping the permission would make PassKeeper useless exactly
+   * where people reuse weak passwords most.
+   *
+   * What is NOT acceptable is filling a credential into a plaintext page on the
+   * public internet, where anyone on the path can read it. Loopback and RFC1918
+   * / RFC4193 / link-local addresses and .local names are treated as acceptable;
+   * every other http:// origin gets a warning in the dropdown before the user
+   * chooses an item.
+   */
+  function _isTrustworthyOrigin() {
+    if (location.protocol === "https:" || location.protocol === "file:") return true;
+    var h = (location.hostname || "").toLowerCase().replace(/^\[|\]$/g, "");
+
+    if (h === "localhost" || h.endsWith(".localhost")) return true;
+    // Reserved TLDs that cannot be registered publicly.
+    if (/\.(local|lan|home|internal)$/.test(h)) return true;
+    // RFC4193 unique-local / RFC4291 link-local IPv6.
+    if (h === "::1") return true;
+    if (/^f[cd][0-9a-f]{2}:/i.test(h) || /^fe80:/i.test(h)) return true;
+
+    // IPv4 must match in FULL. Prefix checks like h.startsWith("127.") also
+    // accept attacker-registrable names such as "127.0.0.1.evil.com", which
+    // would silently suppress the insecure-page warning on a hostile site.
+    var m = h.match(/^(\d{1,3})\.(\d{1,3})\.(\d{1,3})\.(\d{1,3})$/);
+    if (!m) return false;
+    var o = m.slice(1).map(Number);
+    if (o.some(function (n) { return n > 255; })) return false;
+    if (o[0] === 127) return true;                              // loopback
+    if (o[0] === 10) return true;                               // RFC1918
+    if (o[0] === 192 && o[1] === 168) return true;              // RFC1918
+    if (o[0] === 172 && o[1] >= 16 && o[1] <= 31) return true;  // RFC1918
+    if (o[0] === 169 && o[1] === 254) return true;              // link-local
+    return false;
+  }
+
+  /**
+   * Prepend an unmissable warning to the dropdown on plaintext public pages.
+   * Deliberately a warning and not a block: filling is always user-initiated,
+   * and silently offering nothing would look like a broken extension.
+   */
+  function _insecureWarningRow() {
+    if (_isTrustworthyOrigin()) return null;
+    var row = document.createElement("div");
+    Object.assign(row.style, {
+      padding: "8px 12px",
+      background: "#fdecea",
+      color: "#b71c1c",
+      borderBottom: "1px solid #f5c6cb",
+      fontSize: "12px",
+      lineHeight: "1.35",
+    });
+    row.textContent =
+      "⚠ This page is not encrypted (http://). A credential filled here " +
+      "can be read by anyone on the network.";
+    return row;
+  }
+
   function visiblePasswordFields() {
     return Array.from(
       document.querySelectorAll('input[type="password"]'),
@@ -231,24 +301,65 @@
         el.style.outline = "";
       }, 1500);
     });
-    // Autologin: submit the form automatically after filling.
+    // Autologin: submit automatically after filling.
     if (autologin) {
-      const form = pwField.closest("form");
-      if (form) {
       setTimeout(function () {
-          // Prefer clicking a visible submit button so site-specific submit
-          // handlers (React, Vue, etc.) fire correctly.
-          var submitBtn = form.querySelector(
-            '[type="submit"]:not([disabled])',
-          );
-          if (submitBtn) {
-            submitBtn.click();
-          } else {
+        var form = pwField.closest("form");
+        // Prefer clicking a real control so site-specific handlers (React, Vue,
+        // inline onclick) fire — form.submit() bypasses them entirely.
+        var control = _findSubmitControl(pwField);
+        if (control) {
+          control.click();
+        } else if (form) {
           form.submit();
         }
       }, 400);
     }
   }
+
+  // Controls that look like submits but would discard the login instead.
+  var _NEGATIVE_CONTROL = /cancel|reset|back|close|forgot|register|sign\s*up|create/i;
+
+  /**
+   * Find the control that submits the login containing `pwField`.
+   *
+   * Autologin previously required a <form> and did nothing without one, so it
+   * silently never worked on the many login UIs built from plain divs (the ASUS
+   * router admin page submits with
+   * <div class="button" onclick="preLogin();">Sign In</div>).
+   *
+   * Returns null when nothing convincing is found — better to leave the filled
+   * form for the user than to click the wrong thing.
+   */
+  function _findSubmitControl(pwField) {
+    var scope = pwField.closest("form") || pwField.closest('[role="form"]');
+    if (scope) {
+      var explicit = scope.querySelector('[type="submit"]:not([disabled])');
+      if (explicit && isVisible(explicit)) return explicit;
+    }
+
+    // No form (or no explicit submit in it): search progressively wider
+    // ancestors so the nearest plausible control wins.
+    var node = scope || pwField.parentElement;
+    for (var depth = 0; depth < 5 && node; depth++, node = node.parentElement) {
+      var candidates = node.querySelectorAll(
+        'button, [role="button"], [onclick], input[type="submit"], ' +
+          'input[type="button"], div, a',
+      );
+      for (var i = 0; i < candidates.length; i++) {
+        var el = candidates[i];
+        if (el === pwField || el.disabled) continue;
+        if (!_looksLikeSubmitControl(el)) continue;
+        if (!isVisible(el)) continue;
+        // Only leaf-ish controls — a wrapping div can carry a button class.
+        if (el.querySelector("input, button")) continue;
+        var label = (el.textContent || el.value || "").trim();
+        if (label.length > 40) continue;
+        if (_NEGATIVE_CONTROL.test(label)) continue;
+        return el;
+      }
+    }
+    return null;
   }
 
   // ── Icon button (fixed-position, outside the DOM tree of the field) ───────────
@@ -318,6 +429,9 @@
       overflow: "hidden",
     });
 
+    var warning = _insecureWarningRow();
+    if (warning) dropdown.appendChild(warning);
+
     if (panel === "more") {
       buildMorePanel(dropdown, anchorField, pwField, freshItems, filterText);
     } else {

extension/popup/popup.js

@@ -60,11 +60,15 @@ function hideError(elId) {
 }
 
 function escHtml(str) {
+  // " and ' are both required: templates in this file use a mix of
+  // double- and single-quoted attributes, and an unescaped quote of either
+  // kind lets injected text break out of an attribute.
   return String(str ?? "")
     .replace(/&/g, "&")
     .replace(/</g, "&lt;")
     .replace(/>/g, "&gt;")
-    .replace(/"/g, "&quot;");
+    .replace(/"/g, "&quot;")
+    .replace(/'/g, "&#39;");
 }
 
 // Auto-clear clipboard 30 s after a sensitive copy.

migrations/versions/m3n4o5p6q7r8_add_login_attempts.py

@@ -0,0 +1,52 @@
+"""add login_attempts table (per-IP lockout)
+
+Revision ID: m3n4o5p6q7r8
+Revises: l2m3n4o5p6q7
+Create Date: 2026-08-26 00:00:00.000000
+
+Moves failed-login lockout from a global per-account counter to per (account, IP).
+
+The old design was a denial-of-service primitive: anyone who knew an email
+address could send five wrong passwords and lock the real owner out for 15
+minutes, repeatedly and indefinitely, at near-zero cost. Locking someone out of
+their password manager is a serious harm in itself.
+
+Scoping by IP means an attacker locks out only their own address. The legitimate
+owner signing in from their own IP is unaffected, and a distributed attacker
+still faces Flask-Limiter (10/min per IP on /login) plus the Nginx auth_limit
+zone on every address they rotate through.
+
+users.failed_login_count / users.locked_until are left in place and still
+maintained as an aggregate signal for the audit log, but no longer gate
+authentication.
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy.dialects.mysql import INTEGER
+
+
+revision = 'm3n4o5p6q7r8'
+down_revision = 'l2m3n4o5p6q7'
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    op.create_table(
+        'login_attempts',
+        sa.Column('id', INTEGER(unsigned=True), autoincrement=True, primary_key=True),
+        sa.Column('user_id', INTEGER(unsigned=True), nullable=False),
+        sa.Column('ip_address', sa.String(45), nullable=False, server_default=''),
+        sa.Column('failed_count', sa.Integer, nullable=False, server_default='0'),
+        sa.Column('locked_until', sa.DateTime, nullable=True),
+        sa.Column('updated_at', sa.DateTime, nullable=False),
+        sa.ForeignKeyConstraint(['user_id'], ['users.id'], ondelete='CASCADE'),
+        sa.UniqueConstraint('user_id', 'ip_address', name='uq_login_attempt_user_ip'),
+    )
+    # The cleanup job sweeps by updated_at.
+    op.create_index('ix_login_attempts_updated_at', 'login_attempts', ['updated_at'])
+
+
+def downgrade():
+    op.drop_index('ix_login_attempts_updated_at', table_name='login_attempts')
+    op.drop_table('login_attempts')

tests/js/test_field_heuristics.js

@@ -112,6 +112,64 @@ check('click fallback registered', /addEventListener\(\s*"click"/.test(SRC), tru
 check('keydown fallback registered', /addEventListener\(\s*"keydown"/.test(SRC), true);
 check('submit listener retained', /addEventListener\(\s*"submit"/.test(SRC), true);
 
+// ── _isTrustworthyOrigin: where credentials may be filled ──────────────────
+// Extracted from the real source and evaluated against a stubbed `location`,
+// so this exercises the shipped function rather than a copy of its rules.
+{
+  const fnSrc = SRC.match(
+    /function _isTrustworthyOrigin\(\) \{[\s\S]*?\n  \}/,
+  );
+  if (!fnSrc) {
+    failures++;
+    console.log('FAIL  could not extract _isTrustworthyOrigin from content.js');
+  } else {
+    const make = new Function(
+      'location',
+      `${fnSrc[0]}; return _isTrustworthyOrigin();`,
+    );
+    const at = (protocol, hostname) => make({ protocol, hostname });
+
+    // HTTPS is always fine.
+    check('https is trustworthy', at('https:', 'example.com'), true);
+
+    // Local devices over plain HTTP — routers, NAS, printers. Dropping
+    // http://*/* entirely would break exactly these.
+    for (const host of ['localhost', '127.0.0.1', '::1', 'router.local',
+                        '10.0.0.1', '192.168.1.1', '172.16.5.4', '172.31.0.1',
+                        '169.254.1.1', 'nas.lan', 'box.home']) {
+      check(`http://${host} is treated as local`, at('http:', host), true);
+    }
+
+    // Plaintext on the public internet must warn.
+    for (const host of ['example.com', 'bank.co.uk', '8.8.8.8',
+                        '172.15.0.1', '172.32.0.1', '11.0.0.1',
+                        '192.169.1.1', 'evil-localhost.com',
+                        'localhost.evil.com', '127.0.0.1.evil.com']) {
+      check(`http://${host} is NOT trusted`, at('http:', host), false);
+    }
+  }
+}
+
+// ── Autologin must not click a control that discards the login ────────────
+{
+  const m = SRC.match(/var _NEGATIVE_CONTROL = (\/[^\n]+\/[a-z]*);/);
+  if (!m) {
+    failures++;
+    console.log('FAIL  could not find _NEGATIVE_CONTROL in content.js');
+  } else {
+    // eslint-disable-next-line no-eval
+    const NEG = eval(m[1]);
+    for (const label of ['Cancel', 'Reset', 'Go back', 'Forgot password?',
+                         'Register', 'Sign up', 'Create account']) {
+      check(`autologin skips "${label}"`, NEG.test(label), true);
+    }
+    for (const label of ['Sign In', 'Log in', 'Submit', 'Continue', 'OK']) {
+      check(`autologin allows "${label}"`, NEG.test(label), false);
+    }
+  }
+}
+
+// ── Summary (must stay last so every block above is counted) ───────────────
 if (failures) {
   console.log(`\n${failures} failure(s)`);
   process.exit(1);

tests/test_login_lockout.py

@@ -0,0 +1,168 @@
+"""
+Regression tests for the account lockout (two related problems).
+
+1. Disclosure — a locked account answered 429 "Account temporarily locked. Try
+   again in N minute(s)", confirming the address had an account. That is the same
+   leak /register was fixed for, reachable by anyone willing to send five wrong
+   passwords.
+
+2. Denial of service — the lockout was global to the account, so anyone who knew
+   an address could lock the real owner out for 15 minutes, repeatedly and
+   indefinitely. Locking someone out of their password manager is a serious harm
+   on its own.
+
+Lockout is now scoped to (account, source IP): an attacker locks out only
+themselves, and every failure mode returns one identical response.
+"""
+from app import db
+from app.models.audit_log import AuditLog
+from app.models.login_attempt import LoginAttempt
+from app.models.user import User
+from tests.conftest import make_user, register
+
+ATTACKER = '203.0.113.9'
+OWNER = '198.51.100.4'
+
+
+def _login(client, ip, email='user@example.com', auth_hash='AUTH-HASH-V1'):
+    # ProxyFix(x_for=1) makes the rightmost XFF hop the client address, which is
+    # what client_ip() and the lockout key off.
+    return client.post('/api/auth/login',
+                       json={'email': email, 'auth_hash': auth_hash},
+                       headers={'X-Forwarded-For': ip})
+
+
+def _lock_out(client, ip, email='user@example.com'):
+    for _ in range(LoginAttempt.MAX_FAILED):
+        _login(client, ip, email, 'WRONG-HASH')
+
+
+# ── Disclosure ──────────────────────────────────────────────────────────────
+
+def test_locked_response_matches_wrong_password(client, app):
+    make_user(client)
+    _lock_out(client, ATTACKER)
+
+    locked = _login(client, ATTACKER, auth_hash='WRONG-HASH')
+    wrong_on_fresh_ip = _login(client, '203.0.113.77', auth_hash='WRONG-HASH')
+
+    assert locked.status_code == wrong_on_fresh_ip.status_code == 401
+    assert locked.get_json() == wrong_on_fresh_ip.get_json(), (
+        'the locked response is distinguishable, so it discloses the account'
+    )
+
+
+def test_locked_response_matches_unknown_account(client, app):
+    make_user(client)
+    _lock_out(client, ATTACKER)
+
+    locked = _login(client, ATTACKER, auth_hash='WRONG-HASH')
+    unknown = _login(client, ATTACKER, 'nobody@example.com', 'WRONG-HASH')
+
+    assert locked.status_code == unknown.status_code == 401
+    assert locked.get_json() == unknown.get_json()
+
+
+def test_response_never_names_the_lockout(client, app):
+    make_user(client)
+    _lock_out(client, ATTACKER)
+    body = _login(client, ATTACKER, auth_hash='WRONG-HASH').get_json()
+    text = ' '.join(str(v) for v in body.values()).lower()
+
+    for leak in ('locked', 'lockout', 'minute(s) remaining', 'too many'):
+        assert leak not in text, f'response leaks lockout state via {leak!r}: {body}'
+
+
+# ── Denial of service ───────────────────────────────────────────────────────
+
+def test_attacker_cannot_lock_the_owner_out(client, app):
+    """The core DoS fix: the victim's own IP is untouched."""
+    make_user(client)
+    _lock_out(client, ATTACKER)
+
+    assert _login(client, ATTACKER, auth_hash='WRONG-HASH').status_code == 401
+    res = _login(client, OWNER)
+    assert res.status_code == 200, 'the owner was locked out by someone else'
+    assert 'access_token' in res.get_json()
+
+
+def test_lockout_actually_applies_to_the_offending_ip(client, app):
+    """The DoS fix must not have removed brute-force protection."""
+    make_user(client)
+    _lock_out(client, ATTACKER)
+
+    # Even the CORRECT password is refused from a locked-out IP.
+    assert _login(client, ATTACKER).status_code == 401
+
+    row = LoginAttempt.query.filter_by(ip_address=ATTACKER).first()
+    assert row is not None and row.locked_until is not None
+
+
+def test_each_ip_gets_its_own_budget(client, app):
+    make_user(client)
+    _lock_out(client, ATTACKER)
+
+    # A second IP is still four failures away from its own lockout.
+    for _ in range(LoginAttempt.MAX_FAILED - 1):
+        _login(client, '203.0.113.55', auth_hash='WRONG-HASH')
+    assert _login(client, '203.0.113.55').status_code == 200
+
+    assert LoginAttempt.query.filter_by(ip_address=ATTACKER).first().locked_until
+
+
+def test_successful_login_clears_that_ips_history(client, app):
+    make_user(client)
+    for _ in range(LoginAttempt.MAX_FAILED - 1):
+        _login(client, OWNER, auth_hash='WRONG-HASH')
+
+    assert _login(client, OWNER).status_code == 200
+    assert LoginAttempt.query.filter_by(ip_address=OWNER).first() is None, (
+        'failure history survived a successful login, so the next typo locks out'
+    )
+
+
+# ── Bookkeeping ─────────────────────────────────────────────────────────────
+
+def test_lockout_is_audited(client, app):
+    make_user(client)
+    _lock_out(client, ATTACKER)
+
+    entry = (AuditLog.query.filter_by(action='auth.account_locked')
+             .order_by(AuditLog.id.desc()).first())
+    assert entry is not None
+    assert entry.ip_address == ATTACKER
+
+    _login(client, ATTACKER, auth_hash='WRONG-HASH')
+    blocked = (AuditLog.query.filter_by(action='auth.login_blocked')
+               .order_by(AuditLog.id.desc()).first())
+    assert blocked is not None, 'blocked attempts are not recorded'
+
+
+def test_aggregate_counter_still_tracks_all_ips(client, app):
+    """users.failed_login_count no longer gates login but stays informative."""
+    make_user(client)
+    _login(client, ATTACKER, auth_hash='WRONG-HASH')
+    _login(client, '203.0.113.55', auth_hash='WRONG-HASH')
+
+    assert User.query.filter_by(email='user@example.com').first().failed_login_count == 2
+
+
+def test_cleanup_prunes_stale_rows(client, app):
+    from datetime import datetime, timedelta, timezone
+
+    make_user(client)
+    _login(client, ATTACKER, auth_hash='WRONG-HASH')
+    row = LoginAttempt.query.filter_by(ip_address=ATTACKER).first()
+    row.updated_at = (datetime.now(timezone.utc).replace(tzinfo=None)
+                      - timedelta(hours=LoginAttempt.RETENTION_HOURS + 1))
+    db.session.commit()
+
+    assert LoginAttempt.cleanup_expired() == 1
+    db.session.commit()
+    assert LoginAttempt.query.filter_by(ip_address=ATTACKER).first() is None
+
+
+def test_unknown_account_creates_no_rows(client, app):
+    """No user, nothing to track — must not be a way to grow the table."""
+    _login(client, ATTACKER, 'nobody@example.com', 'WRONG-HASH')
+    assert LoginAttempt.query.count() == 0