CVE-2025-22790: Moseter Plugin XSS Vulnerability

CVE-2025-22790 Overview

CVE-2025-22790 is a Reflected Cross-Site Scripting (XSS) vulnerability affecting the WordPress Moseter theme developed by asmedia. This vulnerability allows attackers to inject malicious scripts into web pages viewed by other users through improper neutralization of user-supplied input during web page generation. When exploited, attackers can execute arbitrary JavaScript code in the context of a victim's browser session.

Critical Impact

This reflected XSS vulnerability enables attackers to steal session cookies, redirect users to malicious websites, deface web pages, or perform actions on behalf of authenticated users without their consent.

Affected Products

• WordPress Moseter Theme versions from n/a through 1.3.1

Discovery Timeline

• 2025-05-19 - CVE-2025-22790 published to NVD
• 2026-04-28 - Last updated in NVD database

Technical Details for CVE-2025-22790

Vulnerability Analysis

This vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation). The Moseter WordPress theme fails to properly sanitize user-controlled input before reflecting it back in the HTML response. This allows an attacker to craft a malicious URL containing JavaScript code that executes when a victim clicks the link or visits the specially crafted URL.

The attack requires user interaction, as the victim must be tricked into visiting a malicious link. However, once clicked, the malicious script runs with the same privileges as the legitimate web application, potentially compromising user sessions and sensitive data.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and output encoding within the Moseter theme. User-supplied data is incorporated into the generated HTML page without proper sanitization or escaping, allowing specially crafted input containing JavaScript to be executed by the victim's browser.

Attack Vector

The attack is network-based and requires no prior authentication. An attacker constructs a malicious URL containing XSS payload parameters and distributes it through phishing emails, social media, or other channels. When a victim clicks the link while authenticated to the WordPress site, the injected script executes in their browser context.

The vulnerability can be exploited to hijack user sessions, steal authentication cookies, perform unauthorized actions, or redirect users to attacker-controlled websites. For more technical details on the exploitation mechanism, refer to the Patchstack WordPress Vulnerability Report.

Detection Methods for CVE-2025-22790

Indicators of Compromise

• Unusual URL parameters containing encoded JavaScript or HTML tags in web server access logs
• User reports of unexpected browser behavior, pop-ups, or redirects when visiting the WordPress site
• Web application firewall (WAF) alerts for XSS attack patterns targeting theme-specific endpoints

Detection Strategies

• Implement web application firewall rules to detect and block common XSS payloads in request parameters
• Monitor server access logs for URLs containing suspicious patterns such as <script>, javascript:, or encoded equivalents
• Deploy browser-based security headers including Content-Security-Policy (CSP) to detect and report script injection attempts
• Use security scanning tools to identify vulnerable Moseter theme installations across your infrastructure

Monitoring Recommendations

• Enable detailed logging on WordPress installations to capture all incoming request parameters
• Configure alerting for WAF rule triggers related to XSS attack patterns
• Regularly audit installed themes and plugins for known vulnerabilities using WordPress security plugins
• Monitor for unusual authentication patterns that may indicate session hijacking

How to Mitigate CVE-2025-22790

Immediate Actions Required

• Audit your WordPress installations to identify sites using the Moseter theme version 1.3.1 or earlier
• Consider temporarily disabling or replacing the vulnerable theme until a patched version is available
• Implement Content-Security-Policy headers to restrict inline script execution
• Deploy a Web Application Firewall (WAF) with XSS protection rules enabled

Patch Information

Users should check for updates to the Moseter theme from asmedia. Monitor the Patchstack vulnerability database for patch availability and updated remediation guidance.

Workarounds

• Implement a Content-Security-Policy header that blocks inline scripts and restricts script sources
• Use a WordPress security plugin that provides virtual patching capabilities for known vulnerabilities
• Restrict access to the WordPress admin panel and sensitive areas using IP whitelisting
• Consider switching to an alternative theme if no patch is available from the vendor

# Example Content-Security-Policy header configuration for Apache
# Add to .htaccess or Apache configuration file
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'; img-src 'self' data:; frame-ancestors 'self';"