CVE-2026-4021 | contest-gallery Contest Gallery Plugin up to 28.1.5 on WordPress user_activation_key improper authentication

VDB-352639 · CVE-2026-4021 · GCVE-0-2026-4021 CONTEST-GALLERY CONTEST GALLERY PLUGIN UP TO 28.1.5 ON WORDPRESS USER_ACTIVATION_KEY IMPROPER AUTHENTICATION HISTORYDIFFRELATEJSONXMLCTI CVSS Meta Temp Score Current Exploit Price (≈) CTI Interest Score 6.7 $0-$5k 0.77+ 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., `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. 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. 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 🔒 🔒 🔒 CPE 2.2info 🔒 🔒 🔒 CVSSv4info VulDB Vector: 🔒 VulDB Reliability: 🔍 CVSSv3info VulDB Meta Base Score: 6.8 VulDB Meta Temp Score: 6.7 VulDB Base Score: 5.6 VulDB Temp Score: 5.4 VulDB Vector: 🔒 VulDB Reliability: 🔍 CNA Base Score: 8.1 CNA Vector (Wordfence): 🔒 CVSSv2info Vector Complexity Authentication Confidentiality Integrity Availability Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock Unlock VulDB Base Score: 🔒 VulDB Temp Score: 🔒 VulDB Reliability: 🔍 Exploitinginfo Class: Improper authentication CWE: CWE-287 CAPEC: 🔒 ATT&CK: 🔒 Physical: No Local: No Remote: Yes Availability: 🔒 Status: Not defined Google Hack: 🔒 Price Prediction: 🔍 Current Price Estimation: 🔒 0-Day Unlock Unlock Unlock Unlock Today Unlock Unlock Unlock Unlock Threat Intelligenceinfo Interest: 🔍 Active Actors: 🔍 Active APT Groups: 🔍 Countermeasuresinfo Recommended: Upgrade Status: 🔍 0-Day Time: 🔒 Upgrade: Contest Gallery Plugin 28.1.4 Timelineinfo 03/11/2026 CVE reserved 03/24/2026 +13 days Advisory disclosed 03/24/2026 +0 days VulDB entry created 03/24/2026 +0 days VulDB entry last update Sourcesinfo Advisory: wordfence.com Researcher: Supakiad S. Status: Confirmed CVE: CVE-2026-4021 (🔒) GCVE (CVE): GCVE-0-2026-4021 GCVE (VulDB): GCVE-100-352639 Entryinfo Created: 03/24/2026 02:53 Changes: 03/24/2026 02:53 (68) Complete: 🔍 Cache ID: 99:3EA:101 Discussion No comments yet. Languages: en. Please log in to comment. ◂ PreviousOverviewNext ▸