CVE-2026-67336

better-auth versions before 1.6.11 contain insecure cryptographic defaults in the oidcProvider and mcp plugins that advertise the none algorithm and accept plain PKCE by default. Attackers can exploit algorithm negotiation to accept unsigned tokens or intercept authorization codes when PKCE plain...

GHSA-9H47-PQCX-HJR4 Better Auth has insecure cryptographic defaults in oidcProvider: alg=none advertised and plain PKCE accepted by default

Am I affected? Users are affected if all of the following are true: - Their application uses better-auth at a version below the patched release. - Their application enables oidcProvider from better-auth/plugins/oidc-provider or mcp from better-auth/plugins/mcp the mcp plugin delegates to...