Vulnerability Description
Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11.
CVSS Score
CRITICAL
Affected Products
| Vendor | Product | Versions |
|---|---|---|
| Better-Auth | Better Auth | < 1.6.11 |
Related Weaknesses (CWE)
References
- https://github.com/better-auth/better-auth/commit/1f2ff4215c4affff0b140b0c0a712cPatch
- https://github.com/better-auth/better-auth/pull/9576Issue TrackingPatch
- https://github.com/better-auth/better-auth/releases/tag/v1.6.11Release Notes
- https://github.com/better-auth/better-auth/security/advisories/GHSA-pw9m-5jxm-xrMitigationVendor Advisory
FAQ
What is CVE-2026-53512?
CVE-2026-53512 is a vulnerability with a CVSS score of 9.1 (CRITICAL). Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates...
How severe is CVE-2026-53512?
CVE-2026-53512 has been rated CRITICAL with a CVSS base score of 9.1/10. This is considered a critical vulnerability requiring immediate attention.
Is there a patch for CVE-2026-53512?
Check the references section above for vendor advisories and patch information. Affected products include: Better-Auth Better Auth.