CVE-2025-31455: Limit Max IPs Per User XSS Vulnerability

CVE-2025-31455 Overview

CVE-2025-31455 is an Improper Neutralization of Input During Web Page Generation (Cross-site Scripting) vulnerability affecting the WordPress plugin "Limit Max IPs Per User" developed by ralxz. This DOM-Based XSS vulnerability allows attackers to inject malicious scripts that execute in the context of a victim's browser session, potentially leading to session hijacking, credential theft, or further malicious actions against WordPress site administrators.

Critical Impact

DOM-Based XSS vulnerability enables attackers to execute arbitrary JavaScript in the browser context of authenticated WordPress users, potentially compromising administrative sessions and site integrity.

Affected Products

• Limit Max IPs Per User plugin version 1.5 and earlier
• WordPress installations with vulnerable plugin versions

Discovery Timeline

• April 1, 2025 - CVE-2025-31455 published to NVD
• April 15, 2026 - Last updated in NVD database

Technical Details for CVE-2025-31455

Vulnerability Analysis

This vulnerability is classified as CWE-79: Improper Neutralization of Input During Web Page Generation, specifically manifesting as a DOM-Based Cross-Site Scripting (XSS) vulnerability. DOM-Based XSS occurs when client-side JavaScript processes untrusted data and writes it to the DOM without proper sanitization, causing the browser to execute malicious scripts.

In the context of the Limit Max IPs Per User plugin, the vulnerability exists in how the plugin handles user-supplied input within the WordPress administrative interface. Unlike reflected or stored XSS, DOM-Based XSS occurs entirely within the client-side code, making it particularly insidious as the malicious payload may not be visible in server-side logs.

Root Cause

The root cause of this vulnerability lies in insufficient input sanitization and output encoding within the plugin's JavaScript code. The Limit Max IPs Per User plugin fails to properly neutralize user-controlled input before incorporating it into the Document Object Model (DOM). This allows specially crafted input to be interpreted as executable JavaScript code rather than benign data.

WordPress plugins that manipulate DOM elements based on URL parameters, form inputs, or other user-controllable data sources are particularly susceptible to this class of vulnerability when proper encoding functions are not applied.

Attack Vector

The attack vector for this DOM-Based XSS vulnerability involves an attacker crafting a malicious URL or input that, when processed by the vulnerable plugin's client-side JavaScript, results in script execution. A typical attack scenario includes:

1. Attacker identifies the vulnerable parameter in the Limit Max IPs Per User plugin
2. Attacker crafts a malicious URL containing JavaScript payload
3. Attacker distributes the malicious link to WordPress administrators via phishing or social engineering
4. When an authenticated administrator clicks the link, the malicious JavaScript executes in their browser context
5. The attacker can steal session cookies, perform administrative actions, or inject persistent backdoors

Due to the nature of DOM-Based XSS, the malicious payload is processed entirely by the victim's browser, making detection more challenging than traditional reflected XSS attacks. For detailed technical information about the vulnerability, refer to the Patchstack security advisory.

Detection Methods for CVE-2025-31455

Indicators of Compromise

• Suspicious URL parameters containing JavaScript code or HTML entities targeting the Limit Max IPs Per User plugin pages
• Unexpected outbound connections from administrator browsers to unknown domains
• Modified plugin files or injected scripts in the WordPress installation
• Unusual administrative actions performed without administrator knowledge

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect XSS payloads in URL parameters and request bodies
• Monitor browser console logs for JavaScript errors related to DOM manipulation in plugin contexts
• Deploy Content Security Policy (CSP) headers to detect and prevent inline script execution
• Utilize SentinelOne Singularity XDR for endpoint detection of suspicious browser-based script execution

Monitoring Recommendations

• Enable WordPress security logging to track administrative actions and plugin interactions
• Monitor network traffic for anomalous patterns following administrator access to plugin settings
• Implement real-time alerting for changes to critical WordPress files and configurations
• Review access logs for requests containing common XSS payload signatures targeting plugin endpoints

How to Mitigate CVE-2025-31455

Immediate Actions Required

• Audit your WordPress installation for the presence of the Limit Max IPs Per User plugin version 1.5 or earlier
• Consider temporarily disabling the plugin until a patched version is available
• Implement Content Security Policy headers to mitigate the impact of XSS vulnerabilities
• Review administrator session logs for any suspicious activity that may indicate prior exploitation

Patch Information

Organizations should monitor the official WordPress plugin repository and the Patchstack vulnerability database for updates regarding a patched version of the Limit Max IPs Per User plugin. Until a security update is released, implementing the workarounds below is strongly recommended.

Workarounds

• Implement strict Content Security Policy (CSP) headers that restrict inline script execution and limit script sources
• Use a Web Application Firewall (WAF) to filter malicious XSS payloads targeting the plugin
• Restrict administrative access to the WordPress backend via IP allowlisting
• Consider using an alternative plugin with similar functionality until a patch is available
• Educate administrators about phishing risks and suspicious links

# Example Content Security Policy header configuration for Apache
# Add to .htaccess or Apache configuration
Header set Content-Security-Policy "default-src 'self'; script-src 'self' 'unsafe-eval'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; object-src 'none'; frame-ancestors 'self';"