CVE-2026-53518
HIGHBetter Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption
Title source: cnaDescription
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.
References (3)
Core 3
Core References
X_Refsource_Confirm x_refsource_confirm
https://github.com/better-auth/better-auth/security/advisories/GHSA-7w99-5wm4-3g79
X_Refsource_Misc x_refsource_misc
https://github.com/better-auth/better-auth/commit/b4bc65a007784b2eb0efb459e5fa6fd8055d3ec9
X_Refsource_Misc x_refsource_misc
https://github.com/better-auth/better-auth/releases/tag/v1.6.11
Scores
CVSS v3
8.1
EPSS
0.0023
EPSS Percentile
13.9%
Attack Vector
NETWORK
CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:N
CISA SSVC
Vulnrichment
Exploitation
none
Automatable
no
Technical Impact
total
Details
CWE
CWE-362
CWE-367
Status
published
Products (5)
better-auth/better-auth
>= 1.6.0, < 1.6.11
better-auth/better-auth\/oauth-provider
1.6.0 - 1.6.11
better-auth/better_auth
1.6.0 - 1.6.11
better-auth/oauth-provider
1.6.0 - 1.6.11npm
npm/better-auth
0 - 1.6.11npm
Published
Jul 15, 2026
Tracked Since
Jul 15, 2026