CVE-2025-3625 is an authorization bypass vulnerability identified in Moodle versions 4.3.0, 4.4.0, and 4.5.0. Moodle is a widely used open-source learning management system (LMS) that facilitates online education and training. This vulnerability arises from improper handling of user-controlled keys, which attackers can manipulate to bypass authorization controls. Specifically, the flaw allows unauthorized actors to access sensitive student information and disrupt legitimate users' access by preventing them from logging into their accounts, even after successful two-factor authentication (2FA). The vulnerability compromises the integrity of the authentication and authorization mechanisms, undermining the security assurances provided by 2FA. Although no known exploits are currently observed in the wild, the vulnerability's nature suggests that an attacker with knowledge of the system could exploit it remotely without requiring elevated privileges or complex user interaction beyond initial access. The absence of a CVSS score necessitates an assessment based on the impact on confidentiality, integrity, availability, ease of exploitation, and scope of affected systems. Given Moodle's extensive deployment in educational institutions globally, including Europe, this vulnerability poses a significant risk to the confidentiality of student data and the availability of educational services.

For European organizations, particularly educational institutions and universities relying on Moodle for course delivery and student management, this vulnerability could lead to unauthorized disclosure of sensitive personal data, including academic records and personal identifiers. The ability to prevent legitimate users from logging in, even after 2FA, can disrupt educational continuity, causing operational downtime and loss of trust among students and staff. Data breaches could also result in regulatory penalties under GDPR due to exposure of personally identifiable information (PII). Furthermore, the disruption of access could be exploited for targeted denial-of-service attacks against critical educational infrastructure. The impact extends beyond confidentiality and availability to potentially damaging the integrity of academic records if unauthorized modifications are possible. The medium severity rating reflects these risks, but the actual impact could escalate if exploited at scale or combined with other attack vectors.

1. Immediate patching: Organizations should monitor Moodle's official channels for security patches addressing CVE-2025-3625 and apply them promptly once available. 2. Access controls: Implement strict role-based access controls (RBAC) within Moodle to limit the exposure of sensitive information to only essential personnel. 3. Monitoring and logging: Enhance logging of authentication and authorization events to detect unusual access patterns or repeated failed login attempts that may indicate exploitation attempts. 4. Two-factor authentication review: Although 2FA is bypassed in this scenario, reviewing and strengthening 2FA implementation and fallback mechanisms can reduce risk. 5. Network segmentation: Isolate Moodle servers within secure network zones to limit exposure to external threats. 6. Incident response preparedness: Develop and test incident response plans specific to LMS compromise scenarios, including communication strategies for affected users. 7. User education: Inform users about potential phishing or social engineering attempts that could leverage this vulnerability. 8. Temporary mitigations: Until patches are available, consider restricting access to Moodle instances via VPN or IP whitelisting to reduce attack surface.