CVE-2026-5459 in User Frontend Plugin
Summary
by MITRE • 07/08/2026
The User Frontend: AI Powered Frontend Posting, User Directory, Profile, Membership & User Registration plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 4.3.1 via the payment_page() function due to missing validation on the 'user_id' user controlled key. This makes it possible for unauthenticated attackers to activate a free subscription pack for any user on the site, overwriting their existing paid subscription and causing loss of paid features.
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Analysis
by VulDB Data Team • 07/08/2026
The vulnerability exists within the User Frontend plugin for WordPress, specifically affecting versions through 4.3.1, where an insecure direct object reference flaw permits unauthorized access to user resources. This security weakness stems from inadequate input validation within the payment_page() function that processes the 'user_id' parameter without proper authorization checks. The flaw allows attackers to manipulate the user identifier parameter directly in the application's request flow, bypassing normal authentication and authorization mechanisms that should protect user-specific data.
The technical implementation of this vulnerability demonstrates a classic insecure direct object reference pattern where the application relies on user-supplied input to determine which resource to access or modify. When an attacker crafts a malicious request with a targeted user_id value, the system processes this parameter without verifying whether the attacker has legitimate authorization to act on behalf of that particular user account. This direct parameter manipulation enables unauthorized individuals to perform actions that should only be available to authenticated users or administrators.
The operational impact of this vulnerability extends beyond simple data access, as it allows attackers to manipulate subscription statuses across the entire user base. An unauthenticated attacker can exploit this flaw to activate free subscription packs for any user account on the site, effectively overriding existing paid subscriptions and stripping away premium features that users have paid for. This creates a significant financial loss for both the website operator and paying customers who lose access to their purchased services while attackers gain unauthorized access to premium functionality.
The vulnerability aligns with CWE-639 which specifically addresses Insecure Direct Object Reference, representing a serious security flaw that enables attackers to bypass authorization checks and access resources they should not be permitted to access. From an attack perspective, this vulnerability maps directly to techniques described in the MITRE ATT&CK framework under privilege escalation and credential access domains, where adversaries seek to manipulate application logic to gain unauthorized access to user resources.
To mitigate this vulnerability, developers should implement proper input validation and authorization checks within the payment_page() function, ensuring that all user_id parameters are validated against legitimate user accounts with appropriate permissions. The system must enforce strict authentication requirements before allowing any subscription modifications, including implementing proper session management and role-based access controls. Additionally, parameterized queries and input sanitization should be enforced throughout the application to prevent manipulation of critical parameters. Regular security audits and code reviews focused on authorization logic can help identify similar vulnerabilities across other functions within the plugin that may be susceptible to similar direct object reference attacks.