CVE-2025-4513 in User Key Authentication Plugin
Summary
by MITRE • 05/10/2025
A vulnerability classified as problematic was found in Catalyst User Key Authentication Plugin 20220819 on Moodle. Affected by this vulnerability is an unknown functionality of the file /auth/userkey/logout.php of the component Logout. The manipulation of the argument return leads to open redirect. The attack can be launched remotely. The exploit has been disclosed to the public and may be used. The vendor was contacted early about this disclosure but did not respond in any way.
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Analysis
by VulDB Data Team • 05/10/2025
This vulnerability resides within the Catalyst User Key Authentication Plugin version 20220819 for Moodle, specifically targeting the logout functionality. The issue manifests in the /auth/userkey/logout.php file where improper input validation allows attackers to manipulate the return parameter, creating an open redirect condition that can be exploited to redirect users to malicious websites. The vulnerability represents a classic example of insecure redirect handling that falls under CWE-601, which specifically addresses open redirect vulnerabilities in web applications. This weakness enables attackers to craft malicious URLs that appear legitimate but redirect users to phishing sites or exploit other vulnerabilities on the target domain. The attack vector is entirely remote, meaning no local access or user interaction beyond visiting a malicious link is required for exploitation. The public disclosure of this exploit significantly increases the risk to organizations using affected Moodle installations, as attackers can now leverage this vulnerability without requiring any special privileges or complex attack chains. The lack of vendor response to early disclosure attempts compounds the severity of the situation, leaving affected organizations without official patches or mitigation guidance. This vulnerability directly impacts the integrity of user authentication flows and can be used as a stepping stone for more sophisticated attacks within the targeted environment. The open redirect condition creates opportunities for credential harvesting, malware distribution, and social engineering campaigns that can undermine the security posture of educational institutions relying on Moodle platforms.
The operational impact of this vulnerability extends beyond simple redirection attacks, as it can be leveraged to create convincing phishing scenarios that exploit user trust in legitimate Moodle interfaces. Attackers can craft URLs that appear to originate from the target Moodle installation but redirect users to malicious domains designed to capture credentials or install malware. This represents a significant risk to user data protection and can compromise the overall security of the learning management system. The vulnerability's classification as problematic by the CVE system indicates a moderate to high severity threat that requires immediate attention from system administrators. Organizations running affected Moodle versions must consider this vulnerability as a potential entry point for broader attacks against their educational infrastructure. The absence of vendor response creates additional operational challenges, as security teams cannot rely on official patches or security advisories to address the issue. This leaves administrators with limited options for mitigation, potentially forcing them to implement custom workarounds or temporarily disable the affected authentication plugin until proper solutions are available. The vulnerability's disclosure status means that threat actors are actively exploiting this weakness, making immediate action critical for maintaining system integrity and protecting user data.
Mitigation strategies for this vulnerability should focus on immediate defensive measures while awaiting potential vendor patches or official guidance. Organizations should implement URL validation and sanitization for all redirect parameters within the Moodle authentication system, particularly targeting the logout functionality. Network-level controls such as web application firewalls can be configured to block suspicious redirect patterns and monitor for exploitation attempts. The implementation of Content Security Policy headers can help prevent unauthorized redirects by restricting where pages can redirect users. Security teams should conduct immediate vulnerability scans to identify all instances of the affected plugin version and assess the overall security posture of their Moodle installations. Disabling the user key authentication plugin temporarily may be necessary until proper patches are available, though this requires careful planning to avoid disrupting legitimate user access. Regular monitoring of security advisories and threat intelligence feeds is essential for tracking any developments related to this vulnerability. The implementation of multi-factor authentication can provide additional protection layers even if the redirect vulnerability is exploited. Organizations should also consider implementing user education programs to raise awareness about suspicious redirects and phishing attempts. This vulnerability demonstrates the importance of maintaining up-to-date security patches and having robust vendor communication channels for reporting critical security issues. The lack of vendor response highlights the need for organizations to maintain independent security assessment capabilities and have contingency plans for situations where vendors fail to respond appropriately to security disclosures. Incident response procedures should be updated to include specific protocols for handling open redirect vulnerabilities in authentication systems, ensuring rapid response to potential exploitation attempts.