CVE-2026-24900 MarkUs has a submission-view IDOR exposes all student submissions

Medium 6.5 Published 9 Feb 2026 Updated 10 Feb 2026

Attackers can view arbitrary student submission files by manipulating file IDs due to missing authorization checks in MarkUs.

Exploited in the wild: Not known
Login needed: Any signed-in user
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-24900?

CVE-2026-24900 is a medium-severity missing authorization vulnerability in MarkUsProject Markus, published on 9 Feb 2026. Any signed-in user can exploit it over the network, with no action from the victim.

Official description

MarkUs is a web application for the submission and grading of student assignments. Prior to 2.9.1, the courses/<:course_id>/assignments/<:assignment_id>/submissions/html_content accepted a select_file_id parameter to serve SubmissionFile objects containing a record of files submitted by students. This parameter was not correctly scoped to the requesting user, allowing users access arbitrary submission file contents by id. This vulnerability is fixed in 2.9.1.

Weakness: CWE-639

Which versions are affected by CVE-2026-24900?

It affects 1 product.

Products include Markusproject Markus.

How do I fix CVE-2026-24900?

No fix has been published for CVE-2026-24900 yet. Limit exposure of the affected software until one is available.

Upgrade, and check permissions on every request on the server, not only in the interface. More about Missing authorization.

Is CVE-2026-24900 being exploited?

There is no known exploitation of CVE-2026-24900 in the wild and no public exploit code.

Sources

Also known as GHSA-56gh-8hmq-7q88.