CVE-2025-31442: Keywords Highlighter XSS Vulnerability

CVE-2025-31442 Overview

CVE-2025-31442 is a reflected Cross-Site Scripting (XSS) vulnerability in the Search engine keywords highlighter WordPress plugin (keywords-highlight-tool) developed by e1tekoap42. The flaw affects all plugin versions up to and including 0.1.3. The plugin fails to properly neutralize user-supplied input during web page generation, classified under [CWE-79]. Attackers can craft malicious URLs containing JavaScript payloads. When a victim clicks the link, the payload executes in the victim's browser within the context of the vulnerable site. The vulnerability is exploitable over the network without authentication but requires user interaction to trigger.

Critical Impact

Successful exploitation allows attackers to execute arbitrary JavaScript in a victim's browser, enabling session theft, credential harvesting, and unauthorized actions on behalf of the user.

Affected Products

• WordPress Plugin: Search engine keywords highlighter (keywords-highlight-tool)
• All versions from n/a through 0.1.3
• Vendor: e1tekoap42

Discovery Timeline

• 2025-04-03 - CVE-2025-31442 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-31442

Vulnerability Analysis

The vulnerability stems from improper neutralization of user input during web page generation in the Search engine keywords highlighter plugin. The plugin reflects attacker-controlled input from HTTP request parameters back into the rendered HTML response without applying output encoding or input sanitization. This allows injection of arbitrary HTML and JavaScript into the page context.

The attack requires user interaction, meaning a victim must click a crafted link or visit a malicious page that triggers the request. The scope is changed, indicating that the injected script can affect resources beyond the vulnerable component's security context. According to EPSS data, the vulnerability sits in the 71st percentile for exploitation probability.

Root Cause

The root cause is the absence of output encoding when reflecting search query parameters into the response. The plugin's keyword highlighting feature reads parameters intended to indicate search engine referral terms and inserts them directly into the page DOM. Without escaping characters such as <, >, ", and ', attackers can break out of the intended HTML context and inject executable script tags or event handlers.

Attack Vector

An attacker crafts a URL pointing to a page on the target WordPress site that includes a malicious payload in the keyword parameter consumed by the plugin. The attacker distributes the link via phishing emails, social media, or compromised third-party sites. When a logged-in administrator or visitor clicks the link, the plugin renders the payload inline. The injected JavaScript executes with the privileges of the victim's browser session, enabling cookie theft, session hijacking, or forced administrative actions through CSRF-style follow-on requests.

No verified public exploit code is available for this issue. See the Patchstack Vulnerability Advisory for additional technical context.

Detection Methods for CVE-2025-31442

Indicators of Compromise

• Web server access logs containing requests to WordPress pages with URL parameters embedding <script>, javascript:, or HTML event handlers such as onerror= and onload=.
• Unusual referrer values or query strings containing URL-encoded payloads like %3Cscript%3E directed at pages using the keywords-highlight-tool plugin.
• Outbound requests from user browsers to attacker-controlled domains following visits to affected WordPress pages.

Detection Strategies

• Inspect WordPress installations for the presence of the keywords-highlight-tool plugin at version 0.1.3 or earlier using plugin inventory scans.
• Deploy Web Application Firewall (WAF) rules that flag reflected XSS patterns in query parameters targeting WordPress endpoints.
• Review browser console logs and Content Security Policy (CSP) violation reports for blocked inline script execution attempts.

Monitoring Recommendations

• Monitor administrative session activity for anomalous actions following clicks on external links, such as unexpected user creation or plugin installations.
• Enable HTTP request logging with full query string capture to support retrospective hunting for exploit attempts.
• Alert on WordPress audit log entries indicating privileged actions originating from unusual IP addresses or geolocations.

How to Mitigate CVE-2025-31442

Immediate Actions Required

• Disable or remove the Search engine keywords highlighter plugin from all WordPress sites until a patched version is verified.
• Audit administrator accounts and rotate session cookies and credentials for any user who may have interacted with suspicious links.
• Apply a Content Security Policy (CSP) that restricts inline script execution and limits permitted script sources.

Patch Information

At the time of publication, no fixed version beyond 0.1.3 has been confirmed in the available advisory data. Site administrators should consult the Patchstack Vulnerability Advisory for updated patch availability and vendor communications.

Workarounds

• Deploy a WAF with reflected XSS signatures to filter malicious payloads in query parameters before they reach WordPress.
• Enforce a strict CSP header that disallows unsafe-inline script execution on pages served by the vulnerable plugin.
• Train administrators and editors to avoid clicking unverified links to the WordPress site, particularly while authenticated.

# Example Content Security Policy header to mitigate reflected XSS
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none'; base-uri 'self'; frame-ancestors 'self';"