CVE-2025-62399 identifies a security vulnerability in Moodle’s authentication mechanisms, specifically in its mobile and web service endpoints. The issue stems from insufficient restrictions on the number of consecutive password attempts allowed, enabling attackers to conduct brute-force attacks to guess user credentials. The vulnerability affects Moodle versions 4.1.0, 4.4.0, 4.5.0, and 5.0.0. Because the authentication endpoints do not implement adequate throttling or lockout controls, attackers can repeatedly attempt passwords without being blocked or delayed. The vulnerability does not require prior authentication or user interaction, increasing its exploitability. While the vulnerability does not directly compromise confidentiality or integrity, it can severely impact availability by overwhelming authentication services or locking out legitimate users through forced account lockouts. The CVSS 3.1 score of 7.5 (AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H) indicates network attack vector, low attack complexity, no privileges or user interaction required, and a high impact on availability. No public exploits have been reported yet, but the vulnerability’s presence in widely used Moodle versions makes it a critical concern for educational institutions and organizations using Moodle for training and learning management.

The primary impact of CVE-2025-62399 is on the availability of Moodle authentication services. Successful brute-force attacks can lead to denial of service conditions by overwhelming the authentication system or triggering account lockouts, disrupting access for legitimate users. This can cause significant operational downtime for educational institutions, corporate training environments, and any organization relying on Moodle for critical learning management functions. Although confidentiality and integrity are not directly compromised, the disruption of service can affect business continuity, user productivity, and trust in the platform. Additionally, brute-force attempts may serve as a precursor to credential stuffing or account takeover attacks if weak or reused passwords are present. The vulnerability’s ease of exploitation and lack of required authentication make it a high-risk threat globally, especially in sectors heavily dependent on Moodle for remote learning and training.

Organizations should immediately implement rate limiting and account lockout mechanisms on Moodle authentication endpoints to restrict excessive login attempts. Employing CAPTCHA challenges after a threshold of failed attempts can further deter automated brute-force attacks. Monitoring and alerting on unusual authentication patterns will help detect and respond to attack attempts promptly. Updating Moodle to patched versions once available is critical; in the meantime, administrators can apply custom security plugins or web application firewall (WAF) rules to block or throttle repeated login attempts. Encouraging strong, unique passwords and enabling multi-factor authentication (MFA) where possible will reduce the risk of credential compromise. Network-level protections such as IP reputation filtering and geo-blocking suspicious traffic can also reduce exposure. Regular security audits and penetration testing should verify that authentication controls are effective and resilient against brute-force attacks.