OAuth Single Sign On – SSO (OAuth Client) <= 7.1.2 - Unauthenticated Authentication Bypass

The OAuth Single Sign On – SSO (OAuth Client) plugin for WordPress is vulnerable to Authentication Bypass in all versions up to, and including, 7.1.2. This is due to missing enforcement of the email-verification claim when the claim is absent from the IdP response, because the old inline check was gated on isset($resource_owner[$idp_email_verified_key]) and skipped silently when the claim was not present. This makes it possible for unauthenticated attackers to gain access to an account without a verified email address by authenticating through an OAuth provider that omits the email-verification claim from its response, causing the verification check to be silently bypassed. The 'email verified' check must be enabled in the plugin settings (mo_oauth_email_verify_check).

This one needs no account at all, which puts it outside what login hardening can reach; WordSec's login security narrows the account-level paths around it, and the firewall is what inspects the request itself. None of that substitutes for the fix: OAuth Single Sign On 7.1.3 closes this, and updating the plugin is the step that ends it.

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