CVE-2016-5014 in Moodle
Summary
by MITRE
In Moodle 2.x and 3.x, an unenrolled user still receives event monitor notifications even though they can no longer access the course.
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Analysis
by VulDB Data Team • 05/14/2026
The vulnerability described in CVE-2016-5014 represents a significant access control flaw within the Moodle learning management system that affects versions 2.x and 3.x. This issue stems from a failure in the event monitoring and notification system where users who have been removed from a course continue to receive notifications about course activities and events. The core problem lies in the system's inability to properly synchronize user enrollment status with notification delivery mechanisms, creating a scenario where unauthorized access to information can occur through indirect means.
This technical flaw operates at the intersection of user permission management and event notification systems, specifically violating the principle of least privilege and proper access control. The vulnerability allows unenrolled users to maintain access to course-related information through notification channels, effectively bypassing the normal enrollment and permission checking mechanisms that should prevent such access. From a cybersecurity perspective, this represents a privilege escalation vulnerability that could potentially expose sensitive educational content to individuals who should not have access to it, particularly in environments where course materials contain confidential or proprietary information.
The operational impact of this vulnerability extends beyond simple information disclosure, as it undermines the fundamental security model of the learning management system. When users receive notifications about course events they can no longer access, it creates potential for data leakage, information gathering, and could enable further attacks such as social engineering or targeted phishing attempts. The vulnerability also impacts the integrity of the course management system by allowing inconsistent states where notification systems operate independently from enrollment status, potentially leading to confusion among legitimate users and administrators who may not immediately recognize the security breach.
From a standards perspective, this vulnerability aligns with CWE-284, which addresses improper access control, and represents a failure in implementing proper authorization checks. The issue also relates to ATT&CK technique T1078 which covers valid accounts, as it allows unauthorized access through legitimate notification channels. The root cause demonstrates poor separation of concerns between the user management subsystem and the notification subsystem, where the notification system fails to properly validate user permissions against the current enrollment status. This type of vulnerability is particularly concerning in educational environments where Moodle systems often contain sensitive student data, assessment materials, and proprietary course content that should remain protected from unauthorized access.
The mitigation strategy for this vulnerability requires immediate implementation of proper enrollment status validation within the notification system, ensuring that event monitoring and notification delivery mechanisms check current user permissions before sending any course-related alerts. Administrators should implement regular audits of user access and notification settings, while the system should automatically invalidate notification subscriptions for users who are removed from courses. Additionally, the system should enforce proper session management and access control checks at notification delivery time, ensuring that only enrolled users receive course-specific notifications. This fix should be implemented through proper code review and security testing to prevent similar issues in other notification-based subsystems within the platform.