CVE-2021-4402 in Multiple Roles Plugin
Summary
by MITRE • 07/01/2023
The Multiple Roles plugin for WordPress is vulnerable to Cross-Site Request Forgery in versions up to, and including, 1.3.1. This is due to missing or incorrect nonce validation on the mu_add_roles_in_signup_meta() and mu_add_roles_in_signup_meta_recently() functions. This makes it possible for unauthenticated attackers to add additional roles to users via a forged request granted they can trick a site administrator into performing an action such as clicking on a link.
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Analysis
by VulDB Data Team • 04/10/2026
The Multiple Roles plugin for WordPress presents a critical cross-site request forgery vulnerability that affects versions up to and including 1.3.1. This weakness stems from inadequate security controls within the plugin's core functionality, specifically in the mu_add_roles_in_signup_meta() and mu_add_roles_in_signup_meta_recently() functions. The vulnerability exploits the absence of proper nonce validation mechanisms that should verify the authenticity of user actions and prevent unauthorized modifications to user permissions. Attackers can leverage this flaw to manipulate user roles without authentication, potentially escalating privileges and gaining unauthorized access to sensitive administrative functions.
The technical implementation of this vulnerability demonstrates a failure in applying fundamental web security principles. The plugin's functions lack proper nonce verification, which is a standard security measure designed to prevent CSRF attacks by ensuring that requests originate from legitimate sources within the application. According to CWE-352, this represents a classic cross-site request forgery vulnerability where the application fails to validate that requests are initiated by authenticated users. The absence of nonce validation creates a pathway for attackers to forge requests that appear legitimate to the WordPress application, allowing them to manipulate user role assignments.
Operational impact of this vulnerability extends beyond simple privilege escalation, potentially enabling attackers to gain administrator-level access to affected WordPress installations. When an authenticated administrator clicks on a malicious link or performs an action that triggers the vulnerable functions, the attacker can inject additional roles into user accounts, effectively bypassing normal access controls. This vulnerability aligns with ATT&CK technique T1078.004 which covers valid accounts and privilege escalation through role manipulation. The attack vector relies on social engineering tactics to trick administrators into performing actions, making it particularly dangerous as it requires minimal technical expertise from the attacker while potentially providing maximum access to the compromised system.
Mitigation strategies should prioritize immediate plugin updates to versions that address the nonce validation deficiencies, as this represents the most direct solution to the vulnerability. Organizations should implement additional security measures including regular security audits of installed plugins, monitoring for unauthorized role modifications, and maintaining up-to-date security patches across all WordPress components. The vulnerability highlights the importance of proper input validation and authentication checks in web applications, particularly when handling sensitive user permission modifications. Administrators should also consider implementing additional security layers such as web application firewalls and strict access controls to limit the potential impact of similar vulnerabilities in other components of the WordPress ecosystem.