CVE-2025-31442: Search Keywords Highlighter XSS Flaw

CVE-2025-31442 Overview

CVE-2025-31442 is a Reflected Cross-Site Scripting (XSS) vulnerability in the WordPress plugin "Search engine keywords highlighter" (keywords-highlight-tool) developed by e1tekoap42. The vulnerability arises from improper neutralization of user-supplied input during web page generation, allowing attackers to inject malicious scripts that execute in the context of a victim's browser session.

Critical Impact

Attackers can exploit this Reflected XSS vulnerability to steal session cookies, hijack user accounts, redirect users to malicious sites, or perform actions on behalf of authenticated users including administrators.

Affected Products

• Search engine keywords highlighter (keywords-highlight-tool) versions through 0.1.3
• WordPress installations with the vulnerable plugin activated

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

This vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The Search engine keywords highlighter plugin fails to properly sanitize or encode user-controlled input before reflecting it back in the generated HTML output. When a user visits a specially crafted URL containing malicious JavaScript, the script executes within their browser context with the same privileges as the web application.

The network-accessible nature of this vulnerability means attackers can distribute malicious links through phishing emails, social media, or compromised websites. While user interaction (clicking the malicious link) is required, successful exploitation can impact confidentiality, integrity, and availability of the affected WordPress site and its users' data.

Root Cause

The root cause stems from insufficient input validation and output encoding within the keywords-highlight-tool plugin. The plugin processes search engine referrer keywords or URL parameters without proper sanitization before rendering them in the HTML response. This allows JavaScript payloads embedded in specially crafted URLs to be executed when victims click malicious links.

Attack Vector

The attack vector is network-based, requiring an attacker to craft a malicious URL containing JavaScript payload and trick a victim into clicking it. Since this is a Reflected XSS vulnerability, the payload is not stored on the server but is immediately reflected back in the server's response.

A typical attack scenario involves an attacker creating a URL with malicious script in a vulnerable parameter, then distributing this URL to potential victims through phishing campaigns or watering hole attacks. When a logged-in WordPress administrator clicks the link, the attacker's JavaScript executes with administrative privileges, potentially allowing full site compromise.

Detection Methods for CVE-2025-31442

Indicators of Compromise

• Suspicious URL parameters containing encoded JavaScript or HTML tags in requests to WordPress sites using the keywords-highlight-tool plugin
• Web server access logs showing unusual query strings with <script>, javascript:, onerror=, or other XSS payloads
• User reports of unexpected redirects or browser behavior after clicking links to the WordPress site
• Anomalous session activity following visits from external referrers with suspicious URLs

Detection Strategies

• Deploy Web Application Firewall (WAF) rules to detect and block common XSS payload patterns in URL parameters
• Implement Content Security Policy (CSP) headers to mitigate the impact of successful XSS exploitation
• Monitor web server logs for requests containing URL-encoded script tags or JavaScript event handlers
• Use browser-based XSS auditors and security headers to detect reflected content injection attempts

Monitoring Recommendations

• Enable detailed logging for all WordPress plugin activities and HTTP request parameters
• Set up alerts for unusual patterns in referrer URLs or query strings containing script-like content
• Monitor for unauthorized administrative actions that may indicate successful XSS exploitation
• Implement real-time security monitoring with SentinelOne Singularity to detect post-exploitation activities

How to Mitigate CVE-2025-31442

Immediate Actions Required

• Deactivate and remove the Search engine keywords highlighter (keywords-highlight-tool) plugin immediately if running version 0.1.3 or earlier
• Review WordPress user sessions and consider invalidating all active sessions as a precaution
• Audit recent administrative actions for any unauthorized changes that may indicate compromise
• Implement a Web Application Firewall with XSS protection rules as an additional layer of defense

Patch Information

At the time of publication, no patch has been released for this vulnerability. The affected versions include all releases from the initial version through 0.1.3. WordPress site administrators should monitor the Patchstack WordPress Vulnerability Advisory for updates on available fixes. Until a patch is available, removing the vulnerable plugin is the recommended course of action.

Workarounds

• Remove the keywords-highlight-tool plugin entirely until a security patch is available
• Implement strict Content-Security-Policy headers to prevent inline script execution: Content-Security-Policy: default-src 'self'; script-src 'self'
• Deploy WAF rules to filter requests containing common XSS payloads targeting the plugin's endpoints
• Consider alternative WordPress plugins for keyword highlighting functionality that are actively maintained and security-audited

# WordPress CLI commands to disable and remove the vulnerable plugin
wp plugin deactivate keywords-highlight-tool --path=/var/www/html/wordpress
wp plugin delete keywords-highlight-tool --path=/var/www/html/wordpress

# Add Content-Security-Policy header in .htaccess (Apache)
# Header set Content-Security-Policy "default-src 'self'; script-src 'self'"