CVE-2024-1987 in WP-Members Membership Plugin
Summary
by MITRE • 03/08/2024
The WP-Members Membership Plugin plugin for WordPress is vulnerable to Stored Cross-Site Scripting via the plugin's shortcode(s) in all versions up to, and including, 3.4.9.1 due to insufficient input sanitization and output escaping on user supplied attributes. This makes it possible for authenticated attackers with contributor-level and above permissions to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page.
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Analysis
by VulDB Data Team • 04/17/2025
The WP-Members Membership Plugin for WordPress represents a widely used solution for managing user memberships and access control on wordpress websites. This plugin enables administrators to create membership levels, restrict content access, and manage user permissions through various shortcode implementations. The vulnerability identified in version 3.4.9.1 and earlier affects the plugin's shortcode processing functionality, which serves as a core mechanism for displaying membership-related content and controlling access to protected resources. The issue stems from inadequate input validation and output sanitization within the plugin's shortcode handling code, creating a persistent security flaw that can be exploited by malicious actors with contributor-level privileges or higher.
The technical flaw manifests as a stored cross-site scripting vulnerability that occurs when user-supplied attributes are processed through the plugin's shortcode implementation. When administrators or contributors create or modify content using these shortcodes, the plugin fails to properly sanitize input parameters before storing them in the database. This stored data is then retrieved and rendered without adequate output escaping, allowing malicious scripts to be permanently embedded within the website's content. The vulnerability affects all versions up to and including 3.4.9.1, indicating a long-standing issue that has not been addressed in the plugin's codebase. The flaw operates at the application layer and specifically targets the plugin's shortcode processing engine, which is responsible for interpreting user attributes and generating dynamic content.
The operational impact of this vulnerability is significant for WordPress sites utilizing the WP-Members plugin, as it allows authenticated attackers to execute arbitrary scripts in the context of other users' browsers. This creates a persistent threat where malicious actors can inject malicious code that will execute whenever any user accesses pages containing the compromised shortcode data. The vulnerability is particularly dangerous because it requires only contributor-level permissions, which are often granted to trusted users who may not be fully vetted or monitored. Attackers can leverage this to perform session hijacking, steal cookies, redirect users to malicious sites, or even install malware on users' systems. The stored nature of the vulnerability means that the malicious code remains active until the compromised content is manually removed, creating a long-term threat vector for affected websites.
This vulnerability aligns with CWE-79 which specifically addresses cross-site scripting flaws in software applications. The issue also maps to ATT&CK technique T1566.001 which covers social engineering via malicious content injection. Organizations using this plugin face heightened risk during routine content management activities where contributors may unknowingly introduce malicious scripts through legitimate shortcode usage. The vulnerability creates a persistent backdoor that can be exploited by attackers who gain access to contributor accounts, potentially leading to full site compromise. Security best practices recommend immediate patching of this vulnerability as it represents a critical exposure that can be exploited by attackers with relatively low privileges. The attack surface expands significantly when considering that many websites have multiple contributors with varying levels of security awareness, making this a particularly concerning flaw for organizations managing user-generated content through the plugin's shortcode functionality.
Mitigation strategies should include immediate patching to version 3.4.9.2 or later, which contains the necessary security fixes. Administrators should also implement strict content review processes for contributor accounts, particularly when dealing with shortcode usage. Monitoring for unusual shortcode modifications and implementing web application firewalls can provide additional protection layers. Regular security audits of plugin installations and user permissions should be conducted to identify potential exploitation vectors. The vulnerability demonstrates the critical importance of input sanitization and output escaping in web applications, particularly for plugins that handle user-generated content through shortcode mechanisms. Organizations should also consider implementing privilege least-privilege principles to minimize the potential impact of compromised contributor accounts.