Description
Tinyauth is an authentication and authorization server. Prior to 5.1.0, an unauthenticated remote attacker can send POST /api/user/login requests with 257 distinct nonexistent usernames to fill MaxLoginAttemptRecords and activate a global login lockdown. internal/controller/user_controller.go loginHandler passes each attacker-controlled identifier to internal/service/auth_service.go RecordLoginAttempt, which invokes lockdownMode after the map reaches its cap. IsAccountLocked checks that global state before validating unrelated accounts, causing valid users to receive HTTP 429 until auth.loginTimeout expires, approximately 300 seconds by default. The attack can be repeated, but existing authenticated sessions are not invalidated. This issue is fixed in version 5.1.0.
References7
- github.com/tinyauthapp/tinyauth/commit/654b5cc436fc67865c1f55ed…
- github.com/tinyauthapp/tinyauth/commit/dade1e2c8f27a23df56ac216…
- github.com/tinyauthapp/tinyauth/pull/1008
- github.com/tinyauthapp/tinyauth/pull/943
- github.com/tinyauthapp/tinyauth/releases/tag/v5.1.0
- github.com/tinyauthapp/tinyauth/security/advisories/GHSA-9xhm-w…
- github.com/tinyauthapp/tinyauth/security/advisories/GHSA-9xhm-w…
Metrics
- CVSS 3.1
-
5.3
MEDIUM
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L - EPSS — exploit probability
- 1% percentile: 49 · as of 8 November 2026
- CWE
- CWE-307
Could this be exploited in your environment?
A patch closes the known hole. A penetration test shows what an attacker can still reach — with proof.