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Vulnerability record · CVE-2026-33544 · published 2 April 2026

CVE-2026-33544: Tinyauth race condition vulnerability

Tinyauth · Tinyauth

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.

7.7 CVSS 3.1 High EPSS 0.33% · top 75.8% CWE-362 · Race condition
7.7CVSS 3.1 base score
0.33%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
3References, 1 tagged exploit
17 Jun 2026Last modified by NVD

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:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://github.com/steveiliop56/tinyauth/commit/f26c2171610d5c2dfbba2edb6ccd39490e349803 Patch
https://github.com/steveiliop56/tinyauth/releases/tag/v5.0.5 ProductRelease Notes
https://github.com/steveiliop56/tinyauth/security/advisories/GHSA-9q5m-jfc4-wc92 ExploitMitigationVendor Advisory

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2026-33544), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.