CVE-2026-28405: Markusproject Markus

Medium severity, CVSS 5.4. EPSS: 0.4% chance of exploitation in the next 30 days.

MarkUs is a web application for the submission and grading of student assignments. Prior to version 2.9.1, the courses/<:course_id>/assignments/<:assignment_id>/submissions/html_content route reads the contents of a student-submitted file and renders them without sanitization. This issue has been patched in version 2.9.1.

Affected products

• Markusproject Markus: before 2.9.1 (fixed in 2.9.1)

Published 2026-03-05. Last modified 2026-06-17.