CVE-2026-81198 in MasterStudy LMS Plugin
Summary
by MITRE • 09/02/2026
The MasterStudy LMS WordPress Plugin WordPress plugin before 3.7.46 does not properly verify ownership of a curriculum object before acting on it, allowing authenticated users with the instructor role to delete or modify curriculum sections and materials belonging to courses owned by other instructors.
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Analysis
by VulDB Data Team • 09/02/2026
The vulnerability identified in MasterStudy LMS versions prior to 3.7.46 represents a critical failure in access control mechanisms within the WordPress ecosystem. This plugin, widely used for creating online learning platforms, suffered from an insecure direct object reference issue that allowed authenticated users with specific privileges to manipulate resources they did not own. Specifically, the application failed to verify whether the instructor attempting to modify or delete curriculum sections and materials was actually the owner of those assets. In a multi-instructor environment where multiple educators manage content on a single platform, this lack of ownership verification creates a significant security gap that undermines data integrity and user trust.
From a technical perspective, the flaw resides in how the backend processes requests related to curriculum management. When an instructor sends a request to delete or update a specific course module, section, or material, the application logic relies on identifiers provided by the client without cross-referencing these against database records that establish ownership relationships. This oversight allows for IDOR attacks where an attacker can simply alter the unique identifier of the target resource in their HTTP requests. By substituting the ID of a curriculum item belonging to another instructor with one they control or know, the application processes the action as valid because it does not check if the requesting user has permission over that specific object. This is a classic example of broken access control where the server trusts client-supplied data without sufficient validation against server-side state and permissions.
The operational impact of this vulnerability is severe for institutions relying on MasterStudy LMS to host sensitive educational content. An attacker with an instructor account can delete curriculum sections belonging to colleagues, effectively disrupting their courses and causing loss of instructional material that may not be easily recoverable depending on backup policies. Furthermore, the ability to modify these elements allows for unauthorized changes to course structures, potentially altering learning paths or injecting malicious content into legitimate courses. This compromises the confidentiality, integrity, and availability of educational data. For students enrolled in affected courses, this could result in interrupted learning experiences or exposure to manipulated materials, eroding confidence in the platform's reliability and security posture.
This vulnerability aligns with CWE-639, which describes Authorization Bypass Through User-Controlled Key, a common category for IDOR flaws where access control decisions are made based on user-controlled input without proper verification of authority. Additionally, it maps to MITRE ATT&CK technique T1078, specifically Valid Accounts and potentially T1485 if the modification leads to data destruction or manipulation as part of a broader attack chain. The vulnerability highlights the importance of implementing robust server-side authorization checks that verify not just user authentication but also resource ownership before executing state-changing operations.
To mitigate this issue, administrators must upgrade MasterStudy LMS to version 3.7.46 or later where these access control mechanisms have been corrected. Until an update is applied, it is advisable to restrict instructor privileges as much as possible and monitor logs for unusual patterns of curriculum modification requests that do not correlate with expected user activity. Implementing strict input validation on the server side ensures that every action taken against a resource checks both the identity of the requester and their explicit permission rights over that specific object. Regular security audits focusing on access control logic are essential to prevent similar vulnerabilities in complex web applications where multiple users interact with shared resources.