CVE-2026-33544
Tinyauth has OAuth account confusion via shared mutable state on singleton service instances
HIGH 7.7EPSS 0.3%
Tinyauth is an authentication and authorization server. Prior to version 5.0.5, all three OAuth service implementations (GenericOAuthService, GithubOAuthService, GoogleOAuthService) store PKCE verifiers and access tokens as mutable struct fields on singleton instances shared across all concurrent requests. When two users initiate OAuth login for the same provider concurrently, a race condition between VerifyCode() and Userinfo() causes one user to receive a session with the other user's identity. This issue has been patched in version 5.0.5.
- Affected
- steveiliop56 · tinyauth
- CVSS v3.1 GITHUB
- 7.7 HIGH
CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N - EPSS
- 0.33% chance of exploitation in the next 30 days, 25th percentile
- Published
- 2026-04-02
- Updated
- 2026-04-03
Proof-of-concept exploits (2)
Security advisories
- steveiliop56/tinyauth/security/advisories/GHSA-9q5m-jfc4-wc92
- steveiliop56/tinyauth/commit/f26c2171610d5c2dfbba2edb6ccd39490e349803