Post SMTP – Complete SMTP Solution with Logs, Alerts, Backup SMTP & Mobile App <= 3.6.1 - Missing Authorization to Authenticated (Subscriber+) OAuth Token Update

The Post SMTP plugin for WordPress is vulnerable to authorization bypass in all versions up to, and including, 3.6.1. This is due to the plugin not properly verifying that a user is authorized to update OAuth tokens on the 'handle_gmail_oauth_redirect' function. This makes it possible for authenticated attackers, with subscriber level access and above, to inject invalid or attacker-controlled OAuth credentials. CVE-2025-67563 appears to be a duplicate of this issue.