high8.1
CVE-2026-53518
@better-auth/oauth-provider's OAuth authorization-code grant allows concurrent redemption when two token requests race the find-then-delete primitive
Impact
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.
Affected packages
| Ecosystem | Package | Affected | Fixed in |
|---|---|---|---|
| npm | @better-auth/oauth-provider | >= 1.6.0, < 1.6.11 | 1.6.11 |
| npm | better-auth | < 1.6.11 | 1.6.11 |
Affected products
| Vendor | Product | Affected versions |
|---|---|---|
| Better-Auth | Better-Auth\/Oauth-Provider | from 1.6.0 before 1.6.11 |
| Better-Auth | Better Auth | from 1.6.0 before 1.6.11 |
Weakness classification
References
- NVD record
- CVE.org record
- GitHub advisory
- https://github.com/advisories/GHSA-7w99-5wm4-3g79
- https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79
- https://github.com/better-auth/better-auth/releases/tag/v1.6.11
- https://nvd.nist.gov/vuln/detail/CVE-2026-53518
- https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9