CVE-2026-4110 Overview
CVE-2026-4110 is a Reflected Cross-Site Scripting (XSS) vulnerability affecting the Ultimate WooCommerce Auction Pro WordPress plugin through version 2.4.5. The plugin fails to sanitise and escape a user-supplied parameter before reflecting it in the rendered page. An unauthenticated attacker can craft a malicious URL that executes arbitrary JavaScript in the victim's browser session. The advisory notes the issue can be leveraged against high-privilege users such as administrators, enabling session theft, account takeover, or further compromise of the WordPress site.
Critical Impact
Successful exploitation against an administrator session can lead to WordPress site takeover via injected JavaScript executing in the admin context.
Affected Products
- Ultimate WooCommerce Auction Pro WordPress plugin versions through 2.4.5
- WordPress installations running the vulnerable plugin
- WooCommerce-based storefronts using the auction extension
Discovery Timeline
- 2026-06-22 - CVE-2026-4110 published to NVD
- 2026-06-22 - Last updated in NVD database
Technical Details for CVE-2026-4110
Vulnerability Analysis
The vulnerability is a Reflected Cross-Site Scripting flaw [CWE-79] in the Ultimate WooCommerce Auction Pro plugin. The plugin accepts a request parameter and writes its value back into the HTML response without applying sanitisation or context-appropriate output escaping. When a victim clicks an attacker-crafted link, the browser interprets the injected payload as executable script within the origin of the WordPress site.
Reflected XSS against an authenticated administrator is particularly impactful in WordPress environments. Injected JavaScript can issue authenticated requests to wp-admin endpoints, create new administrator accounts, modify plugins or themes, or exfiltrate session cookies and nonces. The current EPSS probability is 0.152%, reflecting limited observed exploitation interest at the time of publication.
Root Cause
The root cause is missing input sanitisation and missing output escaping on a reflected parameter. WordPress provides functions such as sanitize_text_field() for input handling and esc_html(), esc_attr(), or esc_url() for context-aware output encoding. The vulnerable code path in the plugin omits these protections, allowing raw user input to reach the HTML response stream.
Attack Vector
Exploitation requires user interaction. An attacker delivers a crafted URL containing the malicious parameter value through phishing, a forum post, or another social channel. When an authenticated administrator opens the link, the payload executes in their browser under the WordPress origin. No authentication is required from the attacker, and the scope changes because injected script runs in the victim's privileged session.
No public proof-of-concept code is available. Refer to the WPScan Vulnerability Advisory for technical details.
Detection Methods for CVE-2026-4110
Indicators of Compromise
- Web server access logs showing requests to Ultimate WooCommerce Auction Pro plugin endpoints containing <script>, onerror=, onload=, or URL-encoded equivalents in query parameters
- Unexpected creation of new WordPress administrator accounts or modifications to user roles shortly after admin sessions
- Outbound HTTP requests from admin browser sessions to attacker-controlled domains immediately after navigating a referrer link
Detection Strategies
- Inspect HTTP request logs for query strings targeting the auction plugin with HTML or JavaScript metacharacters such as <, >, ", and javascript:
- Deploy a Web Application Firewall (WAF) rule set that flags reflected XSS payloads against /wp-content/plugins/ultimate-woocommerce-auction-pro/ paths
- Correlate administrator browser referrers with external links to identify potential phishing-delivered XSS chains
Monitoring Recommendations
- Enable WordPress audit logging for user creation, role changes, plugin installation, and theme edits
- Monitor for new or modified files under wp-content/ immediately following an administrator login
- Alert on wp-admin/admin-ajax.php and REST API calls originating from unusual user agents tied to admin sessions
How to Mitigate CVE-2026-4110
Immediate Actions Required
- Identify all WordPress sites running the Ultimate WooCommerce Auction Pro plugin and confirm installed versions
- Deactivate the plugin on any installation running version 2.4.5 or earlier until a fixed release is verified
- Force a password reset and re-issue session tokens for WordPress administrator accounts that may have followed untrusted links
Patch Information
At the time of publication, the WPScan advisory lists versions through 2.4.5 as affected. Administrators should consult the WPScan Vulnerability Advisory and the plugin vendor for the latest patched release and apply the fixed version once published.
Workarounds
- Deactivate and remove the Ultimate WooCommerce Auction Pro plugin until a patched version is installed
- Deploy WAF signatures that block reflected XSS payloads in query parameters targeting plugin endpoints
- Enforce a strict Content Security Policy (CSP) on the WordPress site to limit inline script execution
- Restrict administrator access to trusted networks and require multi-factor authentication for wp-admin logins
Disclaimer: This content was generated using AI. While we strive for accuracy, please verify critical information with official sources.
