CVE-2021-4339 in uListing Plugin
Summary
by MITRE • 06/07/2023
The uListing plugin for WordPress is vulnerable to authorization bypass due to a missing capability check in the "ulisting/includes/route.php" file on the /1/api/ulisting-user/search REST-API route in versions up to, and including, 1.6.6. This makes it possible for unauthenticated attackers to retrieve the list of all users and their email address in the database.
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Analysis
by VulDB Data Team • 07/05/2023
The uListing plugin for WordPress presents a critical authorization bypass vulnerability that fundamentally undermines the security posture of affected installations. This weakness exists within the plugin's REST API implementation where proper access controls have been omitted, allowing malicious actors to exploit a specific endpoint without authentication. The vulnerability affects all versions up to and including 1.6.6, making it a widespread concern for WordPress administrators who have not yet updated their installations. The exposed REST API route at /1/api/ulisting-user/search serves as an entry point for unauthorized data exfiltration, creating a significant risk for websites that rely on this plugin for user management and listing functionalities.
The technical flaw manifests in the missing capability check within the ulisting/includes/route.php file, specifically targeting the user search functionality. This oversight means that any attacker can access the user directory through the REST API endpoint regardless of their authentication status or role permissions. The vulnerability operates at the application layer and directly violates fundamental security principles of access control and authentication. According to CWE-284, this represents an improper access control scenario where the system fails to properly enforce authorization checks, while the ATT&CK framework would categorize this under privilege escalation techniques that leverage API endpoints. The implementation error occurs during the route registration process where the necessary capability verification is completely absent, leaving the endpoint wide open to exploitation.
The operational impact of this vulnerability extends beyond simple information disclosure, creating potential downstream security risks for affected websites and their users. Unauthenticated attackers can systematically harvest user data including email addresses, which serves as a valuable asset for social engineering campaigns, credential stuffing attacks, and other malicious activities. This vulnerability essentially transforms the WordPress installation into a data source for threat actors, who can then use the collected information for targeted attacks against users. The exposure of user email addresses creates a vector for phishing attempts, account takeover efforts, and other forms of targeted cyberattacks that can significantly impact user trust and organizational security. The scope of affected users depends on the size of the WordPress installation and the number of registered users within the system.
Mitigation strategies for this vulnerability require immediate action from WordPress administrators to address the root cause through plugin updates. The most effective solution involves upgrading to a patched version of the uListing plugin where the missing capability check has been implemented and properly enforced. Security teams should also consider implementing additional defensive measures such as API rate limiting, monitoring for unusual access patterns to REST endpoints, and network-level restrictions that limit access to sensitive API routes. Organizations should conduct comprehensive vulnerability assessments to identify other potential API endpoints that may suffer from similar access control issues. The remediation process should include reviewing all plugin configurations and ensuring that proper authentication mechanisms are in place for all exposed API routes. Regular security audits of WordPress installations and plugin ecosystems remain crucial for identifying and addressing similar vulnerabilities before they can be exploited by malicious actors.