CVE-2026-4261 in Expire Users Plugin
Summary
by MITRE • 03/21/2026
The Expire Users plugin for WordPress is vulnerable to Privilege Escalation in all versions up to, and including, 1.2.2. This is due to the plugin allowing a user to update the 'on_expire_default_to_role' meta through the 'save_extra_user_profile_fields' function. This makes it possible for authenticated attackers, with Subscriber-level access and above, to elevate their privileges to that of an administrator.
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Analysis
by VulDB Data Team • 03/21/2026
The Expire Users plugin for WordPress presents a critical privilege escalation vulnerability that undermines the security model of WordPress installations. This vulnerability exists within all versions up to and including 1.2.2, making it a widespread concern for WordPress administrators who have deployed this plugin. The flaw specifically resides in the plugin's handling of user profile metadata, where it fails to properly validate or sanitize input parameters that control user role assignments. The vulnerability manifests through the save_extra_user_profile_fields function which processes user profile updates without adequate authorization checks, creating a path for attackers to manipulate core user permissions.
The technical implementation of this vulnerability stems from insufficient input validation and access control mechanisms within the plugin's codebase. When an authenticated user with Subscriber-level privileges or higher attempts to modify user profile fields through the plugin interface, the system accepts the 'on_expire_default_to_role' meta parameter without proper verification of the requesting user's capabilities. This parameter controls what role a user should be assigned when their account expires, but due to the lack of proper access controls, attackers can manipulate this field to assign administrator privileges to their accounts. The vulnerability represents a classic case of inadequate privilege checking where the plugin assumes that any authenticated user with access to the profile editing interface can make arbitrary changes to user roles, bypassing WordPress's inherent role-based access controls.
The operational impact of this vulnerability extends beyond simple privilege escalation, creating potential for complete system compromise. An attacker with Subscriber-level access can exploit this vulnerability to gain administrator privileges, which provides them with unrestricted access to all WordPress features including plugin management, theme customization, user management, and content modification. This elevated access level allows for persistent backdoor installation, data exfiltration, and the ability to modify or delete critical system components. The vulnerability is particularly dangerous because it requires minimal privileges to exploit and can be leveraged to establish long-term access to the WordPress installation, making it a prime target for attackers seeking to maintain persistence within compromised systems. According to the CWE database, this vulnerability aligns with CWE-284, which describes improper access control, and represents a clear violation of the principle of least privilege in WordPress security architecture.
Mitigation strategies for this vulnerability must address both immediate remediation and long-term security improvements. The most effective immediate solution involves updating to the latest version of the Expire Users plugin where the privilege escalation vulnerability has been patched. Administrators should also implement additional security measures such as restricting access to user profile editing interfaces for non-administrative users, monitoring user role changes through audit logs, and implementing multi-factor authentication for administrative accounts. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically noting how attackers can leverage application-level flaws to gain elevated system access. Organizations should also consider implementing network segmentation and access controls to limit the potential impact of such vulnerabilities, ensuring that even if an attacker gains access to one account, they cannot easily escalate privileges or move laterally within the system. Regular security audits of installed plugins and themes remain essential to identify and remediate similar vulnerabilities before they can be exploited by malicious actors.