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

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Summary

CVECVE-2026-33544
StatePUBLISHED
AssignerGitHub_M
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-04-02 15:16:39 UTC
Updated2026-04-02 15:16:39 UTC
DescriptionTinyauth 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.

Risk And Classification

Primary CVSS: v3.1 7.7 HIGH from [email protected]

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

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

VersionSourceTypeScoreSeverityVector
3.1[email protected]Secondary7.7HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N
3.1CNADECLARED7.7HIGHCVSS:3.1/AV:N/AC:H/PR:L/UI:R/S:C/C:H/I:H/A:N

CVSS v3.1 Breakdown

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

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

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Steveiliop56 Tinyauth affected < 5.0.5 Not specified

References

ReferenceSourceLinkTags
github.com/steveiliop56/tinyauth/security/advisories/GHSA-9q5m-jfc4-wc92 [email protected] github.com
github.com/steveiliop56/tinyauth/releases/tag/v5.0.5 [email protected] github.com
github.com/steveiliop56/tinyauth/commit/f26c2171610d5c2dfbba2edb6ccd3949... [email protected] github.com
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