CVE-2026-77561: CWE-307: Improper Restriction of Excessive Authentication Attempts in tinyauthapp tinyauth
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.
AI Analysis
Technical Summary
CVE-2026-77561 is an improper restriction of excessive authentication attempts vulnerability (CWE-307) in tinyauthapp's tinyauth server. An attacker can send POST /api/user/login requests with 257 distinct nonexistent usernames to fill the MaxLoginAttemptRecords map, triggering a global login lockdown. The lockdown blocks all login attempts by returning HTTP 429 responses until the auth.loginTimeout expires (approximately 300 seconds). This denial-of-service condition affects all users attempting to authenticate, although existing authenticated sessions remain valid. The vulnerability is resolved in version 5.1.0.
Potential Impact
The vulnerability causes a denial of service by preventing valid users from logging in during the lockdown period. It does not affect confidentiality or integrity, nor does it invalidate existing sessions. The impact is limited to availability, causing temporary login disruptions.
Mitigation Recommendations
Upgrade to tinyauth version 5.1.0 or later, where this issue is fixed. No other mitigation is indicated by the vendor advisory.
CVE-2026-77561: CWE-307: Improper Restriction of Excessive Authentication Attempts in tinyauthapp tinyauth
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.
CVSS v3.1
Score 5.3medium
Affected software
tinyauthapp
tinyauth
pkg:github/tinyauthapp/tinyauthRun on your own infrastructure? Check whether these packages are installed with threat-finder — our free open-source scanner.
Weaknesses
AI-Powered Analysis
Machine-generated threat intelligence
Technical Analysis
CVE-2026-77561 is an improper restriction of excessive authentication attempts vulnerability (CWE-307) in tinyauthapp's tinyauth server. An attacker can send POST /api/user/login requests with 257 distinct nonexistent usernames to fill the MaxLoginAttemptRecords map, triggering a global login lockdown. The lockdown blocks all login attempts by returning HTTP 429 responses until the auth.loginTimeout expires (approximately 300 seconds). This denial-of-service condition affects all users attempting to authenticate, although existing authenticated sessions remain valid. The vulnerability is resolved in version 5.1.0.
Potential Impact
The vulnerability causes a denial of service by preventing valid users from logging in during the lockdown period. It does not affect confidentiality or integrity, nor does it invalidate existing sessions. The impact is limited to availability, causing temporary login disruptions.
Mitigation Recommendations
Upgrade to tinyauth version 5.1.0 or later, where this issue is fixed. No other mitigation is indicated by the vendor advisory.
Technical Details
- Data Version
- 5.2
- Assigner Short Name
- GitHub_M
- Date Reserved
- 2026-08-20T20:35:30.146Z
- Cvss Version
- 3.1
- State
- PUBLISHED
Threat ID: 6ab1630f55bf5e2cf5345b95
Added to database: 09/21/2026, 17:02:07 UTC
Last enriched: 09/21/2026, 17:16:30 UTC
Last updated: 09/21/2026, 22:11:59 UTC
Views: 10
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