CVE-2025-46526: My Custom Widgets XSS Vulnerability

CVE-2025-46526 Overview

CVE-2025-46526 is a Reflected Cross-Site Scripting (XSS) vulnerability affecting the My Custom Widgets WordPress plugin developed by janekniefeldt. This vulnerability results 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 execute arbitrary JavaScript code in authenticated users' browsers, potentially leading to session hijacking, credential theft, defacement, or further malicious actions within the WordPress administrative interface.

Affected Products

• My Custom Widgets (mycustomwidget) plugin versions through 2.0.5
• WordPress installations using the vulnerable plugin versions

Discovery Timeline

• 2025-05-23 - CVE-2025-46526 published to NVD
• 2026-04-15 - Last updated in NVD database

Technical Details for CVE-2025-46526

Vulnerability Analysis

This Reflected XSS vulnerability (CWE-79) occurs when the My Custom Widgets plugin fails to properly sanitize or encode user-controlled input before reflecting it back in the rendered HTML response. In a Reflected XSS scenario, the malicious payload is delivered through a crafted URL or form submission, and the server immediately reflects the unsanitized input in the response page.

For WordPress plugins, this type of vulnerability commonly manifests in administrative settings pages, widget configuration forms, or preview functionality where user input is processed and displayed without adequate output encoding. The lack of proper escaping functions such as esc_html(), esc_attr(), or wp_kses() allows script tags or event handlers to be injected and executed.

Root Cause

The root cause of this vulnerability is the improper handling of user input in the My Custom Widgets plugin. The plugin fails to apply WordPress's built-in sanitization and escaping functions when processing and displaying user-supplied data. This allows special characters like <, >, ", and ' to be interpreted as HTML/JavaScript rather than being treated as literal text content.

Attack Vector

In a Reflected XSS attack against this plugin, an attacker crafts a malicious URL containing JavaScript payload in a vulnerable parameter. When a victim (typically a WordPress administrator) clicks this link, the payload executes in their browser session with their privileges. Attack scenarios include:

The attacker sends a phishing email or social engineering message containing the crafted URL. When the administrator clicks the link while authenticated to WordPress, the malicious script executes with their session context. This can lead to cookie theft, session hijacking, or performing administrative actions on behalf of the victim such as creating rogue admin accounts or injecting persistent backdoors.

Detection Methods for CVE-2025-46526

Indicators of Compromise

• Unusual URL parameters containing encoded script tags or JavaScript event handlers in requests to WordPress admin pages
• Suspicious outbound requests from administrator browsers to unknown external domains
• Unexpected changes to WordPress user accounts, themes, or plugin configurations
• Web server logs showing requests with XSS payload patterns targeting the mycustomwidget plugin paths

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS payload patterns in request parameters
• Monitor WordPress audit logs for unauthorized administrative actions following suspicious URL access patterns
• Deploy browser-based XSS protection headers including Content-Security-Policy (CSP) to limit script execution sources
• Review server access logs for requests containing encoded script tags (%3Cscript%3E) or JavaScript event handlers (onerror, onload)

Monitoring Recommendations

• Enable comprehensive logging for all WordPress administrative pages and plugin interactions
• Configure alerts for unusual patterns in URL query parameters, particularly those containing special characters
• Monitor for unexpected outbound network connections originating from administrator browser sessions
• Implement regular security scans of installed WordPress plugins to identify outdated or vulnerable versions

How to Mitigate CVE-2025-46526

Immediate Actions Required

• Update the My Custom Widgets plugin to the latest available version that addresses this vulnerability
• Review WordPress user accounts for any unauthorized additions or privilege escalations
• Audit recent administrative actions for any suspicious changes to site configuration
• Consider temporarily disabling the plugin if no patched version is available until a fix is released

Patch Information

The vulnerability affects My Custom Widgets versions through 2.0.5. Site administrators should check the WordPress plugin repository or the Patchstack WordPress Vulnerability Advisory for information on patched versions and upgrade instructions. Always ensure plugins are updated through official channels.

Workarounds

• Implement a Web Application Firewall with XSS filtering rules to block malicious requests
• Deploy Content-Security-Policy headers to restrict inline script execution and limit allowed script sources
• Restrict access to WordPress administrative areas using IP allowlisting or VPN requirements
• Educate administrators about the risks of clicking untrusted links while authenticated to WordPress

# Add Content-Security-Policy header in Apache .htaccess
Header always set Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';"

# Or in Nginx configuration
add_header Content-Security-Policy "default-src 'self'; script-src 'self'; object-src 'none';" always;