Executive brief
Masteriyo LMS is a WordPress learning management system plugin used to deliver online courses and track student progress. The plugin fails to properly validate permissions on its REST API endpoints, allowing unauthenticated users to enumerate and read any student's enrollment records, course progress, and completion data by guessing sequential record IDs. Enrolled students can also bypass restrictions to view other students' enrollment information.
Technical details
The vulnerability is a broken access control flaw (CWE-862) in the Masteriyo LMS REST API endpoints for retrieving course enrollment records. The single-record endpoint `/masteriyo/v1/users/courses/{id}` lacks authorization checks, allowing unauthenticated attackers to retrieve any enrollment record by iterating sequential IDs—returning HTTP 200 with full enrollment status, timestamps, and per-lesson/quiz progress for valid IDs, and HTTP 404 for non-existent IDs, enabling straightforward enumeration. Additionally, the listing endpoint `/masteriyo/v1/users/courses` accepts a `user[]` parameter that allows any logged-in student to override the default self-scope and request other users' enrollment records. No authentication credentials, nonces, or API keys are required for the unauthenticated path. The fix is available in version 3.4.0 and later.
Affected products
- Masteriyo LMS 1.3.1 to 2.3.3 (fixed in 3.4.0)
Timeline
- 2026-09-07: disclosed
- 2026-09-09: advisory
- 2026-09-09: patched: Fixed in version 3.4.0