CVE-2026-53513: Better-Auth Better-Auth/sso

Critical severity, CVSS 9.6. EPSS: 0.2% chance of exploitation in the next 30 days.

Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.11, the @better-auth/sso plugin's POST /sso/register and POST /sso/update-provider endpoints accept attacker-controlled oidcConfig.userInfoEndpoint, tokenEndpoint, and jwksEndpoint URLs when skipDiscovery: true is set, store them on the ssoProvider row without origin validation, and fetch them during OIDC callback, allowing non-blind server-side request forgery and possible account linking when trustEmailVerified: true is configured. This issue is fixed in version 1.6.11.

Affected products

• Better-Auth Better-Auth/sso: before 1.6.11 (fixed in 1.6.11)
• Better-Auth Better Auth: from 0.1.0, before 1.6.11 (fixed in 1.6.11)

Published 2026-07-15. Last modified 2026-07-21.