CVE-2025-62399 is a vulnerability identified in Moodle versions 4.1.0, 4.4.0, 4.5.0, and 5.0.0, specifically affecting the mobile and web service authentication endpoints. The core issue is the improper restriction of excessive authentication attempts, meaning the system does not adequately limit the number of password guesses an attacker can make. This lack of throttling or lockout mechanisms enables brute-force attacks, where an attacker systematically tries multiple password combinations to gain unauthorized access or disrupt service. While the vulnerability does not directly expose user credentials or allow data modification, it can lead to a denial-of-service (DoS) condition by overwhelming the authentication service with repeated requests. The vulnerability is remotely exploitable over the network without any authentication or user interaction, increasing the attack surface. The CVSS 3.1 score of 7.5 (high) reflects the network attack vector, low attack complexity, no privileges required, no user interaction, and a significant impact on availability. No known exploits have been reported in the wild yet, but the ease of exploitation and the critical role of Moodle in educational environments make this a significant threat. The absence of official patches in the provided data suggests organizations must implement interim mitigations promptly. Given Moodle's widespread use in European educational institutions, this vulnerability poses a risk to the continuity of e-learning services and institutional operations.

For European organizations, particularly educational institutions and e-learning providers relying on Moodle, this vulnerability can cause significant service disruptions. The brute-force attack potential can lead to denial-of-service conditions, making Moodle platforms unavailable to students, educators, and administrators. This impacts the availability of critical educational resources and communication channels, potentially disrupting academic schedules and administrative functions. Although confidentiality and integrity are not directly compromised, the operational impact can be severe, especially during peak usage periods such as exam seasons or enrollment periods. Additionally, repeated brute-force attempts may increase the risk of account lockouts or trigger secondary security controls, complicating user access. The disruption of Moodle services can also affect compliance with educational regulations and contractual obligations related to service availability. Organizations with limited cybersecurity resources or those lacking robust monitoring and incident response capabilities are particularly vulnerable to prolonged outages or cascading effects on other connected systems.

To mitigate CVE-2025-62399, organizations should immediately implement rate limiting on authentication endpoints to restrict the number of login attempts per user or IP address within a defined time window. Deploy account lockout policies that temporarily disable accounts after a threshold of failed login attempts to prevent automated brute-force attacks. Enable multi-factor authentication (MFA) to add an additional layer of security beyond passwords. Monitor authentication logs actively for unusual patterns indicative of brute-force attempts and set up alerts for rapid response. If official patches become available, prioritize their deployment following thorough testing. Employ web application firewalls (WAFs) with rules designed to detect and block brute-force attack patterns targeting Moodle endpoints. Consider integrating CAPTCHA challenges on login forms to deter automated attacks. Educate users on strong password practices and encourage regular password updates. For organizations unable to patch immediately, network-level controls such as IP reputation filtering and geo-blocking of suspicious traffic can reduce exposure. Finally, maintain updated backups and incident response plans to ensure rapid recovery in case of service disruption.