{"cve":"CVE-2026-4021","nvd":{"published":"2026-03-24T00:16:31.210","modified":"2026-06-17T10:55:52.130","status":"Deferred","description":"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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H","score":8.1},"cwes":["CWE-287"],"references":["https://plugins.trac.wordpress.org/browser/contest-gallery/tags/28.1.4/ajax/ajax-functions-frontend.php#L204","https://plugins.trac.wordpress.org/browser/contest-gallery/tags/28.1.4/v10/v10-admin/users/frontend/registry/users-registry-check-after-email-or-pin-confirmation.php#L153","https://plugins.trac.wordpress.org/browser/contest-gallery/trunk/ajax/ajax-functions-frontend.php#L204","https://plugins.trac.wordpress.org/browser/contest-gallery/trunk/v10/v10-admin/users/frontend/registry/users-registry-check-after-email-or-pin-confirmation.php#L153","https://plugins.trac.wordpress.org/changeset?old_path=/contest-gallery/tags/28.1.5&new_path=/contest-gallery/tags/28.1.6"],"products":[],"source":"nvd","synced_at":"2026-10-19T22:26:19.218427112+00:00"},"epss":{"cve":"CVE-2026-4021","score":0.00453,"percentile":0.3935,"date":"2026-10-31"},"kev":null,"osv":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program."]}