Tinyauth: Unauthenticated login attempts can trigger global login lockdown denial of service

MITRE NVD CVE.ORG JSON API

Summary

CVECVE-2026-77561
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-09-21 17:18:52 UTC
Updated2026-09-24 23:19:02 UTC
DescriptionTinyauth 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.

Risk And Classification

Primary CVSS: v3.1 5.3 MEDIUM from [email protected]

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS: 0.006000000 probability, percentile 0.465770000 (date 2026-09-27)

Problem Types: CWE-307 | CWE-307 CWE-307: Improper Restriction of Excessive Authentication Attempts

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L
3.1CNADECLARED5.3MEDIUMCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

CVSS v3.1 Breakdown

Attack Vector
Network
Attack Complexity
Low
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
None
Integrity
None
Availability
Low

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Tinyauthapp Tinyauth affected < 5.1.0 Not specified

References

ReferenceSourceLinkTags
github.com/tinyauthapp/tinyauth/pull/943 [email protected] github.com
github.com/tinyauthapp/tinyauth/releases/tag/v5.1.0 [email protected] github.com
github.com/tinyauthapp/tinyauth/pull/1008 [email protected] github.com
github.com/tinyauthapp/tinyauth/commit/654b5cc436fc67865c1f55edf9ba9fbde... [email protected] github.com
github.com/tinyauthapp/tinyauth/commit/dade1e2c8f27a23df56ac216dcaf4b370... [email protected] github.com
github.com/tinyauthapp/tinyauth/security/advisories/GHSA-9xhm-w3wj-xhqh 134c704f-9b21-4f2e-91b3-4a467353bcc0 github.com
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