CVE-2022-0333 in Moodle
Summary
by MITRE • 01/25/2022
A flaw was found in Moodle in versions 3.11 to 3.11.4, 3.10 to 3.10.8, 3.9 to 3.9.11 and earlier unsupported versions. The calendar:manageentries capability allowed managers to access or modify any calendar event, but should have been restricted from accessing user level events.
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Analysis
by VulDB Data Team • 09/05/2025
The vulnerability identified as CVE-2022-0333 represents a critical access control flaw within the Moodle learning management system that affects multiple version streams including 3.11.4 and earlier, 3.10.8 and earlier, and 3.9.11 and earlier releases. This issue stems from an improper privilege escalation mechanism within the calendar component where the calendar:manageentries capability grants excessive permissions to users with administrative roles. The flaw exists in the permission model that governs calendar event management, specifically allowing users with the calendar:manageentries capability to access and modify calendar events that should be restricted to user-level events only. This misconfiguration creates a significant security gap where unauthorized individuals can potentially view or manipulate calendar entries that contain sensitive user information or personal data. The vulnerability manifests when administrators with the calendar:manageentries capability attempt to access calendar events, bypassing the intended user-level restrictions that should prevent such access to individual user calendar entries.
The technical implementation of this vulnerability lies in the insufficient validation of event ownership within the calendar management system. When users with the calendar:manageentries capability attempt to access calendar events, the system fails to properly verify whether the event belongs to the requesting user or if it represents a user-level event that should remain protected from administrative access. This lack of proper access control validation creates a privilege escalation scenario where managers can view or modify calendar entries that should only be accessible to the event owners. The flaw is categorized under CWE-284 Access Control Issues, specifically representing improper access control mechanisms where the system fails to enforce proper authorization checks. The vulnerability directly impacts the principle of least privilege and could potentially expose sensitive user calendar data, including personal events, scheduled meetings, or private appointments that users expect to remain confidential.
The operational impact of this vulnerability extends beyond simple data exposure to encompass potential privacy violations and unauthorized modifications of user calendar entries. Attackers exploiting this flaw could gain access to sensitive user information contained within calendar events, potentially including personal details, meeting schedules, or private appointments that users would reasonably expect to remain confidential. The ability to modify calendar entries also presents risks of data integrity compromise, where malicious actors could alter event details, reschedule meetings, or create false calendar entries that could disrupt user workflows or provide misleading information. This vulnerability particularly affects educational institutions and organizations that rely heavily on Moodle for their learning management and calendar coordination activities, where calendar events often contain sensitive information about student schedules, faculty meetings, or administrative activities. The flaw could also enable attackers to disrupt organizational operations by manipulating calendar-based scheduling systems or creating confusion through unauthorized calendar modifications.
Organizations utilizing affected Moodle versions should immediately implement mitigations to address this vulnerability through patch management and configuration adjustments. The primary solution involves upgrading to Moodle versions that have addressed this access control flaw, specifically versions beyond the affected releases mentioned in the vulnerability description. System administrators should also review and audit existing user permissions to ensure that calendar:manageentries capabilities are properly restricted to appropriate administrative roles only. Configuration changes may include implementing more granular access controls for calendar events, ensuring that administrative users cannot access user-level calendar entries without explicit authorization. The ATT&CK framework categorizes this vulnerability under privilege escalation techniques, specifically targeting the T1078 Valid Accounts and T1484 Defense Evasion tactics where unauthorized access to calendar data could be used to maintain persistence or evade detection. Organizations should also consider implementing monitoring solutions to detect unauthorized access attempts to calendar entries and establish proper logging of calendar management activities to identify potential exploitation attempts. Additionally, regular security assessments and penetration testing should be conducted to verify that access control mechanisms remain properly configured and that no similar privilege escalation vulnerabilities exist within the Moodle installation or associated systems.