is_auth_enabled() and auth_middleware both caught every exception during
the auth-state probe and returned the "allow" answer instead of denying
the request. Reporter's PoC floods /api/v1/auth/login to exhaust file
descriptors, forcing the next SQLite connect to raise, then hits a
protected endpoint during the fail-open window with no token — granting
unauthenticated access to admin-account creation, API-key creation, DB
backup download, and printer control. CWE-636 / CWE-755. Affects >= 0.1.6.
Fix:
- is_auth_enabled (backend/app/core/auth.py): only returns False for the
legitimate "settings row absent" case; any actual exception propagates
so the caller can deny the request.
- auth_middleware (backend/app/main.py): returns 503 on any probe failure
instead of await call_next(request).
4 new regression tests in test_auth_fail_closed.py pin the contract
(propagates DB exceptions, returns False for no-row, True for "true",
False for "false"). 1 existing security test renamed and updated to
accept either 500 or 503 (both fail-closed) and to verify the
SQLAlchemy detail does not leak in the body.
Codebase grep confirmed no other auth-decision predicate has the same
fail-open shape: _validate_api_key returns None on catch (→ 401 fail-
closed downstream), is_advanced_auth_enabled propagates correctly,
permissions.py has no catch-alls.
Reported by @wondercrash via private advisory.
maziggy
845ad39b19