CVE-2025-13732: s2Member WordPress Plugin XSS Vulnerability

CVE-2025-13732 Overview

The s2Member plugin for WordPress, a popular membership and content restriction solution, contains a Stored Cross-Site Scripting (XSS) vulnerability in the s2Eot shortcode implementation. All versions up to and including 251005 are affected due to insufficient input sanitization and output escaping in the shortcode processing logic.

This vulnerability allows authenticated attackers with Contributor-level privileges or higher to inject malicious JavaScript code into WordPress pages. The injected scripts execute persistently whenever any user, including administrators, views the compromised page.

Critical Impact
Authenticated attackers can inject persistent malicious scripts that execute in the browsers of all site visitors, potentially leading to credential theft, session hijacking, and unauthorized administrative actions.

Affected Products

s2Member WordPress Plugin versions up to and including 251005
WordPress sites utilizing the s2Eot shortcode functionality
Membership-based WordPress installations with Contributor or higher user roles

Discovery Timeline

2026-02-19 - CVE CVE-2025-13732 published to NVD
2026-02-19 - Last updated in NVD database

Technical Details for CVE-2025-13732

Vulnerability Analysis

The vulnerability resides in the s2Eot shortcode handler within the s2Member plugin. The shortcode is designed to display End of Term (EOT) information for membership subscriptions. However, the implementation fails to properly sanitize user-supplied input and escape output when rendering shortcode attributes.

This weakness falls under CWE-79 (Improper Neutralization of Input During Web Page Generation), a classic Stored XSS vulnerability pattern. When a malicious user with at least Contributor-level access creates or edits a page containing the s2Eot shortcode with crafted attributes, the unsanitized content is stored in the WordPress database and subsequently rendered without proper escaping.

The affected code paths can be traced through the plugin's shortcode implementation in the sc-eots-in.inc.php file, where multiple functions process EOT data without adequate security controls.

Root Cause

The fundamental issue stems from missing or inadequate input validation and output encoding in the shortcode processing pipeline. Specifically, the s2Eot shortcode handler does not properly sanitize user-controllable attributes before storing them, nor does it escape the rendered output when displaying the shortcode content to end users. This allows HTML and JavaScript content to pass through unfiltered.

Attack Vector

The attack requires authenticated access with at least Contributor-level permissions on the target WordPress site. An attacker can exploit this vulnerability by:

Logging into WordPress with a Contributor or higher role account
Creating or editing a post/page that uses the s2Eot shortcode
Injecting malicious JavaScript payload through vulnerable shortcode attributes
Publishing or submitting the content for review

Once the malicious content is stored, any user viewing the affected page will have the injected script execute in their browser context. This can lead to session token theft, phishing attacks, malware distribution, or full site compromise if an administrator views the page.

The vulnerability is exploited via a network-based attack requiring low-privilege authentication but no user interaction beyond the victim visiting the compromised page. Due to the stored nature, the malicious payload persists and can impact users across different browser sessions.

Detection Methods for CVE-2025-13732

Indicators of Compromise

Unexpected JavaScript code or <script> tags in post/page content containing s2Eot shortcodes
Unusual shortcode attribute values containing encoded characters, HTML entities, or script payloads
Browser console errors or unexpected network requests when viewing pages with s2Member shortcodes
Reports of suspicious behavior from users after visiting membership-related pages

Detection Strategies

Audit WordPress database for posts containing s2Eot shortcodes with suspicious attribute patterns
Implement Web Application Firewall (WAF) rules to detect XSS payloads in shortcode syntax
Review WordPress activity logs for post modifications by Contributor-level users
Use security scanning tools to identify stored XSS vulnerabilities in WordPress content

Monitoring Recommendations

Enable comprehensive logging for all post creation and modification events in WordPress
Monitor for Content Security Policy (CSP) violations that may indicate XSS execution attempts
Configure alerts for unusual JavaScript execution patterns on membership-related pages
Regularly scan WordPress content database for known XSS payload signatures

How to Mitigate CVE-2025-13732

Immediate Actions Required

Update the s2Member plugin to the latest patched version immediately
Review all existing content using the s2Eot shortcode for malicious payloads
Audit user accounts with Contributor-level or higher permissions
Temporarily disable the s2Eot shortcode functionality if an immediate update is not possible

Patch Information

The vulnerability has been addressed in WordPress Changeset 3430799. Site administrators should update the s2Member plugin through the WordPress admin dashboard or by downloading the latest version from the WordPress plugin repository.

For detailed vulnerability analysis, refer to the Wordfence Threat Intelligence report.

Workarounds

Restrict Contributor-level access to trusted users only until the patch can be applied
Implement Content Security Policy headers to limit the impact of any successfully injected scripts
Use WordPress security plugins to add additional output escaping for shortcode content
Consider temporarily removing or disabling the s2Member plugin if the s2Eot shortcode is not essential

bash

# WordPress CLI command to update s2Member plugin
wp plugin update s2member

# Verify current plugin version
wp plugin get s2member --field=version

# Search for potentially malicious shortcode usage
wp db query "SELECT ID, post_title FROM wp_posts WHERE post_content LIKE '%[s2Eot%script%' OR post_content LIKE '%[s2Eot%javascript%'"