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Contest Gallery EUVDEUVD-2026-14654

| CVE-2026-4021 HIGH
Improper Authentication (CWE-287)
2026-03-23 Wordfence GHSA-m4rm-grq4-j8wp
8.1
CVSS 3.1 · NVD
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Register account with crafted email matching target user ID
  2. Delivery
    Trigger email confirmation handler via `users-registry-check-after-email-or-pin-confirmation.php`
  3. Exploit
    SQL injection matches admin user ID
  4. Execution
    Bypass authentication via `ajax-functions-frontend.php` key-based endpoint
  5. Impact
    Obtain admin session

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A07:2025 - Authentication Failures
ASVS 5.0
V6 - Authentication Authentication mechanism validation
MITRE ATT&CK

2 techniques across 2 tactics: Defense Evasion, Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Contest Gallery plugin for WordPress versions ≤28.1.5 with non-default RegMailOptional=1 setting enabled. Attacker registers with crafted email starting with target user ID. Unauthenticated remote exploitation; no victim interaction required.

Impact

Despite the high CVSS score of 8.1, the real-world risk is somewhat mitigated by the AC:H (High Complexity) rating and the requirement that the non-default RegMailOptional=1 configuration option be enabled. The attack vector is network-based (AV:N) requiring no privileges (PR:N) or user interaction (UI:N), which increases exploitability once the preconditions are met. The impact scope includes high confidentiality, integrity, and availability impacts (C:H/I:H/A:H), as attackers gain full administrative control. No EPSS score or KEV listing is provided in the available data, suggesting this is a newly disclosed vulnerability without evidence of active exploitation in the wild yet. However, the detailed technical references to specific code lines in the WordPress plugin repository (lines 153 and 204) and the availability of a patch in version 28.1.6 indicate that security researchers have thoroughly analyzed the vulnerability. The attack complexity is elevated because it requires specific plugin configuration and knowledge of MySQL type coercion behavior, but the potential for complete site takeover makes this a genuine priority for affected installations. Organizations using Contest Gallery with the optional registration setting enabled should prioritize remediation immediately.

Exploit ScenarioDerived

An unauthenticated attacker identifies a WordPress site running Contest Gallery plugin version 28.1.5 or earlier with the RegMailOptional=1 setting enabled. The attacker registers a new account using the crafted email '1poc@attacker.com' targeting the site administrator whose user ID is 1. During the email confirmation process, MySQL's type coercion converts the email string '1poc@attacker.com' to integer 1 in the WHERE ID = %s clause, causing the admin's user_activation_key to be overwritten with the attacker's known activation key. The attacker then calls the unauthenticated post_cg1l_login_user_by_key AJAX endpoint with their activation key, successfully authenticating as the site administrator and gaining complete control over the WordPress installation to install backdoors, steal data, or deface the site.

This Week Schedule remediation this week. Why: HIGH severity (CVSS 7.0-8.9).
No patch listed yet 0.1% exploitation probability (EPSS)

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AnalysisAIv1 – Mar 23, 2026

The Contest Gallery plugin for WordPress contains an authentication bypass vulnerability that allows unaattacked attackers to take over administrator accounts and gain complete site control. All versions up to and including 28.1.5 are affected when the non-default RegMailOptional=1 setting is enabled. The vulnerability exploits MySQL type coercion by registering with specially crafted email addresses to overwrite admin activation keys, then using an unauthenticated login endpoint to authenticate as the target user. With a CVSS score of 8.1 and high attack complexity (AC:H), this represents a critical risk for sites using the vulnerable configuration.

RemediationAI

Immediately upgrade Contest Gallery plugin to version 28.1.6 or later, which addresses this authentication bypass vulnerability. The patch changeset is documented at https://plugins.trac.wordpress.org/changeset?old_path=/contest-gallery/tags/28.1.5&new_path=/contest-gallery/tags/28.1.6. If immediate patching is not feasible, disable the RegMailOptional=1 setting in the plugin configuration to eliminate the attack vector, as this vulnerability requires this non-default option to be enabled. Additionally, implement web application firewall rules to monitor and block suspicious user registration attempts with email addresses beginning with numeric characters, particularly those matching low user IDs like 1 or 2 which typically correspond to administrator accounts. Review existing user accounts for suspicious registrations with emails starting with numbers and examine authentication logs for unexpected admin login activity using the post_cg1l_login_user_by_key AJAX action.

Affected VersionsENISA

Contest Gallery – Upload & Vote Photos, Media, Sell with PayPal & Stripe * ≤28.1.5

Affected Packages

euvd contest_gallery_upload_vote_photos_media_sell_with_paypal_stripe no fix

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

This vulnerability affects the Contest Gallery plugin for WordPress (CPE: cpe:2.3:a:contest-gallery:contest_gallery_–_upload_&_vote_photos,_media,_sell_with_paypal_&_stripe:*:*:*:*:*:*:*:*). The root cause is CWE-287 (Improper Authentication) stemming from a type confusion issue in users-registry-check-after-email-or-pin-confirmation.php at line 153. The code uses a user-supplied email string in a WHERE ID = %s SQL clause where a numeric user ID is expected. When MySQL performs implicit type coercion, an email like '1poc@example.test' is converted to integer 1, causing the query to target the admin user (typically ID 1) instead of the registering user. This overwrites the admin's user_activation_key field. The vulnerability chain is completed by the post_cg1l_login_user_by_key AJAX action in ajax-functions-frontend.php at line 204, which allows unauthenticated key-based login without proper validation, enabling the attacker to authenticate as the compromised admin account using the activation key they controlled.

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  • Exploit and PoC references, threat intelligence from 22 sources

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Severity by source

NVD PRIMARY 8.1 HIGH
AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Primary rating from NVD · only source for this CVE.

CVSS VectorNVD

Attack Vector
Network
Attack Complexity
High
Privileges Required
None
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

DescriptionCVE.org

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.

Executive ViewAI

Why It Matters

The Contest Gallery WordPress plugin contains a critical authentication bypass vulnerability that could allow attackers to seize administrator accounts and gain complete control of affected websites. Organizations using this plugin with the RegMailOptional setting enabled face immediate risk of account takeover, data theft, and site defacement, with no vendor patch currently available.

Business Impact: Severe
Compensating Controls

Disable the Contest Gallery plugin entirely or set RegMailOptional=0 to disable the vulnerable registration feature; implement Web Application Firewall (WAF) rules to detect and block registration requests with malformed email addresses; restrict direct access to WordPress admin login endpoints via IP whitelisting; monitor admin account activity logs for unauthorized access attempts; enforce multi-factor authentication (MFA) on all administrator accounts; consider disabling user registration functionality if not operationally critical.

Threat Intelligence Overview

EPSS Score
0.1%
Top 69% exploitable
Data Quality
6 sources
Confidence: High

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity HIGH
CISA KEV No
Public POC No
EPSS 0.1%
Patch available No
Active threat No
Deciding rule
HIGH severity (CVSS 7.0-8.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact
Very High
Technical Impact
Total

Priority Score

40
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +40
PoC: 0
Weaponized: 0
Threat intel: 0
Gov advisory: 0

Attack Technique

Authentication bypass attacks exploit flaws in the verification mechanisms that control access to systems and applications.

CVE-2021-24915 CRITICAL POC
9.8 Nov 29

The Contest Gallery WordPress plugin before 13.1.0.6 does not have capability checks and does not sanitise or escape the

CVE-2024-43283 MEDIUM POC
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Insertion of Sensitive Information Into Sent Data vulnerability in Wasiliy Strecker / ContestGallery developer Contest G

CVE-2026-16055 HIGH POC
7.5 Aug 05

Contest Gallery WordPress plugin before version 30.0.7 implements a custom front-end login mechanism that issues authent

CVE-2022-4158 HIGH POC
7.5 Dec 26

The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

CVE-2022-4156 HIGH POC
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The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

CVE-2026-16057 MEDIUM POC
6.5 Aug 03

Post-deletion authorization bypass in the Contest Gallery WordPress plugin before 30.0.7 allows any authenticated Author

CVE-2022-4166 MEDIUM POC
6.5 Dec 26

The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

CVE-2022-4165 MEDIUM POC
6.5 Dec 26

The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

CVE-2022-4164 MEDIUM POC
6.5 Dec 26

The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

CVE-2022-4163 MEDIUM POC
6.5 Dec 26

The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

CVE-2022-4162 MEDIUM POC
6.5 Dec 26

The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

CVE-2022-4161 MEDIUM POC
6.5 Dec 26

The Contest Gallery WordPress plugin before 19.1.5.1, Contest Gallery Pro WordPress plugin before 19.1.5.1 do not escape

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