Summaryinfo

A vulnerability was found in contest-gallery Contest Gallery Plugin up to 28.1.5 on WordPress. It has been rated as critical. Affected by this issue is the function user_activation_key of the file users-registry-check-after-email-or-pin-confirmation.php. This manipulation causes improper authentication. The identification of this vulnerability is CVE-2026-4021. It is possible to initiate the attack remotely. There is no exploit available. Upgrading the affected component is advised.

Detailsinfo

A vulnerability classified as critical was found in contest-gallery Contest Gallery Plugin up to 28.1.5 on WordPress. Affected by this vulnerability is the function user_activation_key of the file users-registry-check-after-email-or-pin-confirmation.php. The manipulation with an unknown input leads to a improper authentication vulnerability. The CWE definition for the vulnerability is CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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., `[email protected]`), 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.

The weakness was shared by Supakiad S.. It is possible to read the advisory at wordfence.com. This vulnerability is known as CVE-2026-4021 since 03/11/2026. The exploitation appears to be difficult. The attack can be launched remotely. The exploitation doesn't need any form of authentication. Technical details of the vulnerability are known, but there is no available exploit.

By approaching the search of inurl:users-registry-check-after-email-or-pin-confirmation.php it is possible to find vulnerable targets with Google Hacking.

Upgrading to version 28.1.4 eliminates this vulnerability.

The vulnerability is also documented in the databases at CNNVD (CNNVD-202603-4628) and EUVD (EUVD-2026-14654). Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Type

• Photo Gallery Software

Vendor

• contest-gallery

Name

• Contest Gallery Plugin

Version

• 28.1.0
• 28.1.1
• 28.1.2
• 28.1.3
• 28.1.4
• 28.1.5

CPE 2.3info

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CPE 2.2info

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