MasterStudy LMS cover deletion permits arbitrary attachment deletion
MasterStudy LMS through 3.7.23 lets an authenticated Instructor call the wp_ajax_stm_lms_delete_cover action with the required nonce and an attacker-chosen sequential file_id. stm_lms_delete_cover() verifies only that a user is logged in and then passes file_id directly to wp_delete_attachment(..., true), without checking that the attachment is the caller's currently assigned cover. An Instructor can therefore permanently delete attachments belonging to other users. The CNA narrative says through 3.7.14, but its structured affected data says through 3.7.23; official tags confirm that 3.7.23 remains vulnerable and 3.7.24 introduces ownership and attachment-type validation.
- Component
- MasterStudy LMS WordPress Plugin – for Online Courses and Education
- Plugin slug
masterstudy-lms-learning-management-system- Affected
- <= 3.7.23
- Safe version
3.7.24- Published
- Jul 29, 2026
This CVE was published Jul 29, 2026 and is one of 31 known issues for this plugin.
Update, patch or deactivate.
Update MasterStudy LMS to 3.7.24 or later. Version 3.7.24 requires file_id to match the current user's stm_lms_user_cover value and verifies that the selected post is an attachment before deletion. Restore missing media from backups and review Instructor activity if attachment IDs may have been enumerated.
A safe version is available, so updating to that version or later is the preferred remediation. If an immediate update is not practical, consider a targeted application patch or temporarily restricting the affected functionality.
Deactivate only when warranted by your risk profile, or when advised by your hosting provider in the limited circumstances where the vulnerability cannot otherwise be mitigated. If you’re unsure which action is appropriate, contact Fused or your hosting provider for guidance.
Technical description
The MasterStudy LMS WordPress Plugin – for Online Courses and Education plugin for WordPress is vulnerable to Insecure Direct Object Reference in all versions up to, and including, 3.7.14. This is due to the `stm_lms_delete_cover()` function lacking ownership validation on the `file_id` parameter before passing it to `wp_delete_attachment()`. This makes it possible for authenticated attackers, with Instructor-level access and above, to delete arbitrary attachments belonging to any user by enumerating sequential attachment IDs.
CVE / CNA vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:H/A:N