CVE-2025-3281 in User Registration & Membership Plugin
Summary
by MITRE • 05/06/2025
The User Registration & Membership – Custom Registration Form, Login Form, and User Profile plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 4.2.1 via the create_stripe_subscription() function, due to missing validation on the 'member_id' user controlled key. This makes it possible for unauthenticated attackers to delete arbitrary user accounts that have registered through the plugin.
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Analysis
by VulDB Data Team • 05/18/2026
The vulnerable plugin represents a critical security flaw in the WordPress ecosystem that affects user account management and authentication processes. This issue stems from insufficient input validation within the create_stripe_subscription() function, which processes user membership data through the plugin's custom registration and profile system. The vulnerability exists across all versions up to and including 4.2.1, making it a widespread concern for WordPress sites utilizing this membership solution. The core problem manifests when the system fails to properly validate the 'member_id' parameter, which is directly controlled by users during the subscription process, creating an insecure direct object reference condition that allows unauthorized access to user account manipulation.
The technical implementation of this vulnerability enables attackers to exploit the missing validation checks by manipulating the 'member_id' parameter in their requests. This parameter should normally be validated against authenticated user sessions or other security controls, but instead the system accepts user-controlled input without proper authorization verification. The vulnerability operates at the application level, specifically targeting the membership plugin's handling of user account data, and allows for arbitrary account deletion operations to be performed without proper authentication. This represents a fundamental breakdown in access control mechanisms that should normally prevent unauthorized users from manipulating other users' accounts.
The operational impact of this vulnerability extends beyond simple account deletion, as it creates a pathway for attackers to potentially disrupt user membership services and compromise the integrity of user data within the system. Unauthenticated attackers can leverage this flaw to target any user account registered through the plugin, effectively allowing them to remove users from the membership system, potentially disrupting legitimate service access for those affected. The vulnerability's severity is amplified by its accessibility to anyone who can access the plugin's subscription endpoint, making it particularly dangerous in environments where the plugin is widely used or where the subscription process is publicly accessible.
Security mitigations for this vulnerability should focus on implementing proper input validation and access control measures within the create_stripe_subscription() function. The system must validate that any member_id parameter is properly authenticated and authorized before allowing account manipulation operations. This aligns with CWE-639: Authorization Bypass Through User-Controlled Key, which specifically addresses insecure direct object references where user-controllable parameters can be used to access unauthorized resources. Organizations should immediately update to patched versions of the plugin, implement proper session validation, and consider additional monitoring for unauthorized account manipulation attempts. The vulnerability also maps to ATT&CK technique T1078.004: Valid Accounts, as it allows attackers to leverage legitimate user accounts for unauthorized operations, though it specifically bypasses normal authentication mechanisms through parameter manipulation rather than account compromise.
This vulnerability highlights the importance of secure coding practices in WordPress plugin development, particularly around input validation and access control implementations. The flaw demonstrates how seemingly simple parameter handling can create significant security risks when proper validation controls are omitted. System administrators should conduct comprehensive security assessments of their WordPress installations to identify similar vulnerabilities in other plugins, as this pattern of insecure direct object reference attacks is common in web applications where user input is not properly validated against authenticated contexts. The vulnerability also underscores the necessity of maintaining current plugin versions and implementing proper security monitoring to detect anomalous account manipulation activities that could indicate exploitation attempts.