The WPO365 | SEAMLESS WORDPRESS + MICROSOFT INTEGRATION (WPO365 | LOGIN) plugin for WordPress is vulnerable to Authentication Bypass via OIDC Nonce Replay in all versions up to, and including, 44.1 This is due to IdTokenServiceDeprecated::processopenidconnecttoken() using the incompatible WordPress core wpverifynonce() function to validate a nonce produced by NonceService::createnonce() — a 64-character hex value that wpverifynonce() can never successfully verify — causing the nonce check to silently fail without terminating authentication, so execution continues into authenticateoidcuser() with the attacker-supplied idtoken. This makes it possible for unauthenticated attackers who have obtained a previously-issued, valid idtoken for a target account to replay that token and authenticate as any WordPress user, including administrators, resulting in full site takeover. This vulnerability is only exploitable when the useidtokenparserv2 plugin option is enabled, as this is the configuration that routes token processing through the deprecated parser containing the broken nonce check.