GHSA-q437-g7fv-2jvv: Lemur user-update path stores plaintext passwords
Summary`lemur.users.service.update()` writes a user's new password as plaintext to the `users.password` column. The `User` model wires bcrypt hashing to SQLAlchemy's `before_insert` event but registers no equivalent listener for `before_update`, and `service.update()` does not call `user.hash_password()` after assigning the new value. Every password change performed through the admin-gated `PUT /api/1/users/<id>` endpoint persists the user's password to the database in cleartext.Root Cause`lemur/users/models.py`:`lemur/users/service.py`:No `before_update` listener exists. `User.password` is a plain `Column(String(128))` with no property setter that hashes on assignment. The bcrypt code path is bypassed entirely on every UPDATE statement that touches this column.Affected Endpoints| Method | Path | Source |
|---|---|---|
| PUT | /api/1/users/`<id>` | lemur/users/views.py:274 (gated by `@admin_permission.require`) |`lemur/auth/views.py:323` also calls `user_service.update()` during SSO/OAuth login, but passes only six positional arguments. `password` defaults to `None` on that path and the `if password:` guard short-circuits. The bug is triggered only through the admin-only PUT handler.ImpactWhen an administrator changes a user's password via `PUT /api/1/users/<id>`, the cleartext password is persisted to `users.password`. Subsequent login attempts for that user will fail (`check_password` calls `bcrypt.check_password_hash` against an unhashed value), pushing operators toward workarounds.The more serious consequence is a defense-in-depth bypass. Bcrypt is the protection that prevents a database compromise from yielding usable credentials. With plaintext rows present, an attacker who exfiltrates the `users` table, a backup, a read replica, or query logs obtains directly usable login credentials — no offline cracking required. Because users reuse passwords across services, the blast radius extends beyond Lemur.The bug specifically affects admin-driven password resets, which are the normal post-incident workflow and exactly when plaintext storage is most harmful.Steps to ReproduceInstall Lemur with default config. Create an admin user and a target user 'alice' (created via the standard flow, password will be hashed correctly on insert).Verify the initial hash:
psql lemur -c "SELECT password FROM users WHERE username='alice';"Output: $2b$12$N9Q...   (bcrypt hash, as expected)As admin, change alice's password via the API:
curl -X PUT https://lemur.local/api/1/users/<alice_id> \
     -H "Authorization: Bearer <admin_jwt>" \
     -H "Content-Type: application/json" \
     -d '{
       "username": "alice",
       "email": "alice@example.com",
       "active": true,
       "profile_picture": null,
       "roles": [{"name": "operator"}],
       "password": "ProofOfConcept_2026"
     }'Read the column again:
psql lemur -c "SELECT password FROM users WHERE username='alice';"Output: ProofOfConcept_2026   ← plaintext, not hashedConfirm the failure mode: 'alice' can no longer log in with 'ProofOfConcept_2026'
because check_password runs bcrypt.check_password_hash() against the cleartext column.RemediationRegister the listener for both events:Alternative, equivalent fix in the service layer:The listener fix is preferred because it closes the gap for any future code path that mutates `user.password`.A one-time migration is recommended to detect and re-hash any rows already stored in cleartext. Bcrypt hashes begin with `$2b$`, `$2a$`, or `$2y$`. Any cleartext credential should be treated as **compromised** — rotate it, do not just re-hash it — since it has been at rest in plaintext and may exist in backups, audit logs, and replicas.
CVSS v3.1: 4.9