CVE-2026-53517
Better Auth OAuth Provider: Refresh Token Rotation Race Condition Allows Concurrent Replay and Token Family Forking
CVSS Score
8.1
EPSS Score
0.0%
EPSS Percentile
0th
Better Auth is an authentication and authorization library for TypeScript. From 1.4.8-beta.7 until 1.6.11, the @better-auth/oauth-provider POST /oauth2/token endpoint on the refresh_token grant performs a non-atomic read, validate, revoke, and mint sequence on the oauthRefreshToken row, allowing concurrent requests with the same parent refresh token to pass the revoked check and create forked refresh-token families; the vulnerable range also includes embedded better-auth plugin versions before 1.6.0. 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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CVSS v3 Breakdown
CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:N Attack Vector
Network
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
None
Affected Versions
better-auth / better-auth
>= 1.4.8-beta.7, < 1.6.0
@better-auth / oauth-provider
>= 1.6.0, < 1.6.11