CVE-2026-41427: Better Auth OAuth 2.1 Provider: Unprivileged users can register OAuth clients
Better Auth is an authentication and authorization library for TypeScript. Prior to 1.6.5, the clientPrivileges option documents a create action, but the OAuth client creation endpoints did not invoke the hook before persisting new clients. Deployments that configured clientPrivileges to restrict client registration were not actually restricted — any authenticated user could reach the create endpoints and register an OAuth client with attacker-chosen redirect URIs and metadata. This vulnerability is fixed in 1.6.5.
Affected Software
Event History
Frequently Asked Questions
What is the severity of CVE-2026-41427?
CVE-2026-41427 is considered a high severity vulnerability due to the risk of unprivileged users registering OAuth clients.
How do I fix CVE-2026-41427?
To fix CVE-2026-41427, upgrade Better Auth to version 1.6.5 or later to ensure proper permissions for OAuth client registration.
What impact does CVE-2026-41427 have on my application?
CVE-2026-41427 allows unprivileged users to register OAuth clients, potentially compromising security and user data.
Is my application affected by CVE-2026-41427?
If your application uses Better Auth versions prior to 1.6.5 and allows OAuth client registration, it is affected by CVE-2026-41427.
What is Better Auth in relation to CVE-2026-41427?
Better Auth is an authentication and authorization library for TypeScript, which contains the vulnerability CVE-2026-41427 affecting OAuth client creation.