CVE-2025-23788: Easy Filter Plugin XSS Vulnerability

CVE-2025-23788 Overview

CVE-2025-23788 is a Reflected Cross-Site Scripting (XSS) vulnerability affecting the Easy Filter WordPress plugin developed by Roni Saha. The vulnerability stems 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

This reflected XSS vulnerability could allow attackers to steal session cookies, hijack user accounts, deface websites, or redirect users to malicious sites when victims click on crafted malicious links.

Affected Products

• WordPress Easy Filter plugin version 1.10 and earlier
• All WordPress installations running vulnerable versions of the easy-filter plugin

Discovery Timeline

• 2025-02-14 - CVE-2025-23788 published to NVD
• 2026-04-23 - Last updated in NVD database

Technical Details for CVE-2025-23788

Vulnerability Analysis

This vulnerability is classified under CWE-79 (Improper Neutralization of Input During Web Page Generation), commonly known as Cross-Site Scripting. The Easy Filter plugin fails to properly sanitize user-controlled input before reflecting it back in the HTML response, creating an opportunity for script injection attacks.

In a reflected XSS scenario, the malicious payload is embedded in a request (typically via URL parameters or form inputs) and immediately reflected in the server's response without proper encoding or validation. When a victim clicks a malicious link containing the payload, the script executes within their browser with full access to the page's DOM and session context.

Root Cause

The root cause of this vulnerability lies in insufficient input validation and output encoding within the Easy Filter plugin. User-supplied data is incorporated into the HTML output without proper sanitization, allowing HTML and JavaScript code to be injected and executed. The plugin fails to implement proper escaping functions such as esc_html(), esc_attr(), or wp_kses() that WordPress provides for secure output handling.

Attack Vector

The attack vector is network-based and requires user interaction. An attacker must craft a malicious URL containing the XSS payload and convince a victim to click the link. This is typically achieved through phishing emails, social engineering, or embedding the malicious link in forums, comments, or other user-generated content areas.

The attack flow involves the attacker constructing a URL with malicious JavaScript embedded in a vulnerable parameter, distributing this link to potential victims, and when clicked, the victim's browser executes the injected script in the context of the vulnerable WordPress site. This can lead to session hijacking, credential theft, or further attacks against the victim.

Detection Methods for CVE-2025-23788

Indicators of Compromise

• Unusual URL parameters containing JavaScript code or HTML tags in requests to WordPress sites using Easy Filter
• Web server logs showing suspicious GET/POST requests with encoded script tags or event handlers
• Browser console errors related to blocked inline scripts if Content Security Policy is in place
• Reports of unexpected pop-ups or redirects from users visiting the affected WordPress site

Detection Strategies

• Implement Web Application Firewall (WAF) rules to detect and block common XSS patterns in URL parameters
• Monitor web server access logs for requests containing suspicious characters like <script>, javascript:, or encoded variants
• Deploy browser-based XSS auditors and Content Security Policy headers to detect and mitigate script injection attempts
• Conduct regular security scans of WordPress installations to identify vulnerable plugin versions

Monitoring Recommendations

• Enable detailed logging of all HTTP requests to WordPress sites running the Easy Filter plugin
• Set up alerts for requests containing potential XSS payloads targeting known vulnerable parameters
• Monitor for unusual spikes in traffic or error rates that may indicate scanning or exploitation attempts
• Review Content Security Policy violation reports if CSP is implemented

How to Mitigate CVE-2025-23788

Immediate Actions Required

• Identify all WordPress installations using the Easy Filter plugin and assess exposure
• Consider temporarily deactivating the Easy Filter plugin until a patched version is available
• Implement Web Application Firewall rules to filter malicious XSS payloads
• Deploy Content Security Policy headers to mitigate the impact of successful XSS attacks

Patch Information

As of the available data, the vulnerability affects Easy Filter version 1.10 and earlier. Site administrators should check the Patchstack WordPress Vulnerability Database for the latest patch status and update the plugin to the most recent version when a fix becomes available. Monitor the WordPress plugin repository for security updates from the developer.

Workarounds

• Deploy a Web Application Firewall with XSS protection rules to filter malicious input
• Implement Content Security Policy headers with strict script-src directives to prevent inline script execution
• Remove or deactivate the Easy Filter plugin if it is not essential to site functionality
• Use WordPress security plugins that provide real-time XSS protection and input sanitization

# Example: Add Content Security Policy header in .htaccess
# This helps mitigate XSS by restricting script sources
Header set Content-Security-Policy "default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline';"