CVE-2026-53518

UNKNOWN 0.0

Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption

CVSS Score

0.0

EPSS Score

0.0%

EPSS Percentile

0th

Better Auth is an authentication and authorization library for TypeScript. From 1.6.0 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint for the authorization_code grant redeems a single-use authorization code through a non-atomic find-then-delete sequence, allowing two concurrent requests to pass the read step and mint independent access tokens, refresh tokens, and ID tokens; legacy /oauth2/token and /mcp/token paths in oidc-provider and mcp plugins share the same primitive. This issue is fixed in version 1.6.11.

CWE	CWE-362 CWE-367
Vendor	better-auth
Product	better-auth
Published	Jul 15, 2026
Last Updated	Jul 15, 2026

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Affected Versions

better-auth / better-auth

>= 1.6.0, < 1.6.11

References

NVD ↗ CVE.org ↗ EPSS Data ↗

github.com: https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79 github.com: https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9 github.com: https://github.com/better-auth/better-auth/releases/tag/v1.6.11