CVSS 3.1
8.1 highCVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:NCVE-2026-53517
High (8.1) in better-auth. EPSS 0.4% chance of exploitation in the next 30 days. Fixed in @better-auth/oauth-provider 1.6.11.
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.
Severity
- EPSS
- 0.4% chance of exploitation in the next 30 days; higher than 36% of CVEs (scores of 2026-10-31)
- CWEs
- CWE-362, CWE-367
- Published
- Modified
- Record from
- the NVD, synced
Affected
- better-auth:better-auth\/oauth-provider
- better-auth:better_auth
Packages (OSV)
| Advisory | Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|---|
| GHSA-392p-2q2v-4372 | npm | @better-auth/oauth-provider | >=1.6.0 <1.6.11 | 1.6.11 |
| GHSA-392p-2q2v-4372 | npm | better-auth | >=1.4.8-beta.7 <1.6.0 | 1.6.0 |