CVE-2026-42657 Overview
CVE-2026-42657 affects the Contest Gallery WordPress plugin in versions up to and including 28.1.7. The issue is categorized under [CWE-1284] (Improper Validation of Specified Quantity in Input) and can be triggered by unauthenticated remote attackers over the network. Successful exploitation results in a limited integrity impact without affecting confidentiality or availability. The flaw was published to the National Vulnerability Database (NVD) on June 15, 2026, following a Patchstack advisory.
Critical Impact
Unauthenticated attackers can reach the affected functionality remotely and trigger an integrity-impacting condition in WordPress sites running Contest Gallery <= 28.1.7.
Affected Products
- Contest Gallery WordPress plugin versions up to and including 28.1.7
- WordPress installations with Contest Gallery enabled
- Sites exposing the plugin endpoints to the public internet
Discovery Timeline
- 2026-06-15 - CVE-2026-42657 published to NVD
- 2026-06-17 - Last updated in NVD database
Technical Details for CVE-2026-42657
Vulnerability Analysis
The vulnerability resides in the Contest Gallery plugin for WordPress. Patchstack classifies it as an "Other Vulnerability Type" mapped to [CWE-1284], meaning the plugin fails to properly validate a specified quantity within user-supplied input. The flaw is reachable without authentication, so any visitor can interact with the vulnerable code path.
The attack vector is Network with low complexity and no privileges or user interaction required. Impact is limited to integrity, with no direct confidentiality or availability consequences reflected in the advisory. The Exploit Prediction Scoring System (EPSS) lists a probability of 0.219% as of June 18, 2026, indicating a low likelihood of near-term mass exploitation.
Root Cause
The root cause is improper validation of a specified quantity in input handled by the plugin. When the plugin receives a request, it does not enforce that the supplied value conforms to expected bounds, types, or counts before processing it. This allows an attacker to submit values the application logic does not expect, modifying server-side state or stored data in ways that compromise integrity.
Attack Vector
An unauthenticated attacker sends crafted HTTP requests to a WordPress site running a vulnerable Contest Gallery version. Because no authentication or user interaction is required, automated scanners can identify and target exposed installations directly. No verified proof-of-concept code or public exploit is currently referenced in the advisory. Site operators should consult the Patchstack WordPress Vulnerability Report for the technical reference.
Detection Methods for CVE-2026-42657
Indicators of Compromise
- Unexpected modifications to Contest Gallery entries, votes, or contest configuration data in the WordPress database.
- Unauthenticated POST or GET requests targeting Contest Gallery plugin endpoints under /wp-content/plugins/contest-gallery/ or related admin-ajax actions.
- Spikes in request volume to plugin handlers from a small number of source IPs.
Detection Strategies
- Inventory WordPress sites and identify any running Contest Gallery <= 28.1.7 using plugin version scanners or wp-cli plugin list.
- Enable WordPress Web Application Firewall (WAF) rules from providers such as Patchstack or equivalents that cover CVE-2026-42657.
- Review web server access logs for anomalous parameter values submitted to Contest Gallery endpoints, particularly malformed or out-of-range numeric inputs.
Monitoring Recommendations
- Forward WordPress and web server logs to a centralized data lake or SIEM and alert on plugin-specific endpoints.
- Monitor database audit logs for unusual write operations against Contest Gallery tables.
- Track plugin file integrity using tools such as wp-cli checksums or file integrity monitoring agents.
How to Mitigate CVE-2026-42657
Immediate Actions Required
- Identify all WordPress instances running Contest Gallery and confirm the installed version.
- Update Contest Gallery to a version newer than 28.1.7 once the vendor publishes a fixed release.
- Apply virtual patching through a WordPress WAF if an upgrade cannot be performed immediately.
Patch Information
At the time of NVD publication, the advisory references the Patchstack WordPress Vulnerability Report as the authoritative source. Administrators should check the WordPress plugin repository for a release greater than 28.1.7 that explicitly addresses CVE-2026-42657 and review the changelog before deployment.
Workarounds
- Deactivate and remove the Contest Gallery plugin until a fixed version is available if the functionality is not business critical.
- Restrict access to plugin endpoints using web server rules, IP allowlists, or authentication proxies in front of WordPress.
- Enable a WordPress security plugin or WAF with virtual patching coverage for CVE-2026-42657.
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
