Contest Gallery <= 28.1.5 - Unauthenticated Privilege Escalation Admin Account Takeover via Registration Confirmation Email-to-ID Type Confusion

Summary

The Contest Gallery plugin for WordPress is vulnerable to an authentication bypass leading to admin account takeover in all versions up to, and including, 28.1.5. This is due to the email confirmation handler in `users-registry-check-after-email-or-pin-confirmation.php` using the user's email string in a `WHERE ID = %s` clause instead of the numeric user ID, combined with an unauthenticated key-based login endpoint in `ajax-functions-frontend.php`. When the non-default `RegMailOptional=1` setting is enabled, an attacker can register with a crafted email starting with the target user ID (e.g., `1poc@example.test`), trigger the confirmation flow to overwrite the admin's `user_activation_key` via MySQL integer coercion, and then use the `post_cg1l_login_user_by_key` AJAX action to authenticate as the admin without any credentials. This makes it possible for unauthenticated attackers to take over any WordPress administrator account and gain full site control.

Timeline

1. Mar 23, 2026, 11:25 PM UTCCVE published
2. Mar 24, 2026, 6:43 PM UTCCISA SSVC assessment

   Exploitation: none · Automatable: no · Technical impact: total

3. Apr 8, 2026, 5:32 PM UTCRecord last updated

Affected versions

• contest-gallery Contest Gallery – Upload & Vote Photos, Media, Sell with PayPal & Stripe

  through 28.1.5

References 6