The @better-auth/oauth-provider package versions in the stable 1.6.x line and pre-releases before 1.7.0-beta.4 allow OAuth clients to request access tokens for audiences (resources) that were not authorized during the initial authorization flow. This occurs because the provider does not bind the requested resource at the authorization endpoint to the token issuance, enabling clients to obtain tokens for any resource in the server's allowlist. The issue affects deployments that configure multiple valid audiences and rely on the audience claim for authorization decisions. The vulnerability is fixed in version 1.7.0-beta.4 and later, which enforce binding of resources to the authorization grant and restrict token issuance accordingly. Workarounds include limiting valid audiences to a single entry and configuring resource servers to reject tokens with unexpected audiences.