CVE-2026-53518 - Better Auth OAuth Provider: Race Condition in Authorization Code Exchange Enables Multi-Use Code Redemption
CVE ID :CVE-2026-53518
Published : July 15, 2026, 6:16 p.m. | 31 minutes ago
Description :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.
Severity: 7.6 | HIGH
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Published : July 15, 2026, 6:16 p.m. | 31 minutes ago
Description :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.
Severity: 7.6 | HIGH
Visit the link for more details, such as CVSS details, affected products, timeline, and more...