Vulnerability details

CVE-2026-33544

steveiliop56 tinyauth

Tinyauth has OAuth account confusion via shared mutable state on singleton service instances

CVSS 3.1

7.7High

Official description

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.

CVSS scores

Score	Version	Source	Vector
7.7High	3.1	CVEProject cvelistV5 (CNA) (GitHub_M)	`CVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N`

Affected products

Vendor	Product	Versions	Source
steveiliop56	tinyauth	< 5.0.5	CVEProject cvelistV5 (CNA)

References and advisories

https://github.com/steveiliop56/tinyauth/security/advisories/GHSA-9q5m-jfc4-wc92 x_refsource_CONFIRM
https://github.com/steveiliop56/tinyauth/commit/f26c2171610d5c2dfbba2edb6ccd39490e349803 x_refsource_MISC
https://github.com/steveiliop56/tinyauth/releases/tag/v5.0.5 x_refsource_MISC

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Details

Published: 2026-04-02
Last updated: 2026-04-03
State: Published
Assigner (CNA): GitHub_M

Exploit prediction (EPSS)

0.35%

Probability of exploitation in 30 days

28.9%

Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable: No
Exploitation: Proof of concept
Technical impact: Total

Weaknesses (CWE)

CWE-362
Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')