CVE-2025-12018 in MembershipWorks Plugin
Summary
by MITRE • 11/12/2025
The MembershipWorks – Membership, Events & Directory plugin for WordPress is vulnerable to Stored Cross-Site Scripting via admin settings in all versions up to, and including, 6.14 due to insufficient input sanitization and output escaping. This makes it possible for authenticated attackers, with administrator-level permissions and above, to inject arbitrary web scripts in pages that will execute whenever a user accesses an injected page. This only affects multi-site installations and installations where unfiltered_html has been disabled.
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Analysis
by VulDB Data Team • 11/13/2025
The vulnerability identified as CVE-2025-12018 affects the MembershipWorks plugin for WordPress, specifically targeting versions up to and including 6.14. This represents a critical security flaw that exploits stored cross-site scripting vulnerabilities within the plugin's administrative settings interface. The vulnerability manifests when authenticated attackers with administrator-level privileges attempt to manipulate the plugin's configuration parameters, creating a persistent threat that can compromise user sessions and execute malicious code within the context of the victim's browser.
The technical root cause of this vulnerability stems from inadequate input sanitization and insufficient output escaping mechanisms within the plugin's codebase. When administrators modify settings through the administrative interface, the plugin fails to properly validate and sanitize user-supplied input before storing it in the database. Additionally, the output escaping mechanisms that should protect against XSS attacks are either missing or improperly implemented, allowing malicious script payloads to be stored and subsequently executed when affected pages are accessed by other users. This flaw directly aligns with CWE-79, which describes Cross-Site Scripting vulnerabilities resulting from insufficient input validation and output encoding.
The operational impact of this vulnerability is particularly severe in multi-site WordPress installations where the attack surface expands significantly. Attackers with administrative access can inject malicious scripts that execute whenever any user accesses pages containing the compromised data, potentially leading to session hijacking, data theft, or further privilege escalation within the WordPress environment. The vulnerability specifically targets installations where unfiltered_html has been disabled, suggesting that the security measures designed to prevent such attacks are being bypassed through the plugin's flawed implementation. This creates a dangerous scenario where even hardened WordPress installations become vulnerable through the plugin's insecure code handling.
The attack vector requires an authenticated administrator-level account, which limits the scope of potential exploiters but does not eliminate the risk entirely. In environments where administrators have elevated privileges across multiple sites or where privilege escalation occurs through other means, this vulnerability can serve as a persistent backdoor for attackers. The stored nature of the XSS payload means that the malicious code remains active until manually removed from the database, potentially affecting numerous users over extended periods. Organizations should consider this vulnerability in their security posture assessments, particularly within environments where the plugin is actively used and where administrative accounts represent high-value targets for attackers.
Mitigation strategies should focus on immediate plugin updates to versions that address the input sanitization and output escaping issues, while also implementing additional security controls such as role-based access restrictions and monitoring for unauthorized administrative changes. The vulnerability demonstrates the critical importance of proper input validation and output encoding practices in web applications, particularly within content management systems where user-generated content processing is common. Organizations should also consider implementing web application firewalls and regular security audits to identify similar vulnerabilities in other plugins and themes that may not have been properly tested for XSS vulnerabilities. The ATT&CK framework categorizes this as a privilege escalation technique through persistent web application vulnerabilities, emphasizing the need for comprehensive security measures beyond traditional perimeter defenses.