CVE-2026-53512 - Better Auth: OAuth refresh-token replay via missing client authentication on oidc-provider and mcp plugins
CVE ID :CVE-2026-53512
Published : July 15, 2026, 6:16 p.m. | 31 minutes ago
Description :Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11.
Severity: 9.1 | CRITICAL
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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. Prior to 1.6.11, the legacy oidcProvider and mcp plugins expose OAuth token endpoints whose refresh_token grant authenticates only possession of the bound refreshToken row and matching client_id, without verifying the confidential client's client_secret, allowing an attacker with a valid refresh_token to mint access tokens and rotated refresh tokens through /api/auth/oauth2/token or /api/auth/mcp/token. The @better-auth/oauth-provider package is not affected. This issue is fixed in version 1.6.11.
Severity: 9.1 | CRITICAL
Visit the link for more details, such as CVSS details, affected products, timeline, and more...