CVE-2026-25057 Zip Slip in MarkUs config upload allowing RCE

Critical 9.1 Published 9 Feb 2026 Updated 10 Feb 2026

Instructors can achieve remote code execution by uploading a malicious zip file with path traversal entries in the MarkUs assignment configuration upload feature.

Exploited in the wild: Not known
Login needed: An administrator
Attackable: Over the internet
Victim action needed: Not needed
Fix: None listed

What is CVE-2026-25057?

CVE-2026-25057 is a critical path traversal vulnerability in MarkUsProject Markus, published on 9 Feb 2026. An attacker needs administrator access to exploit it, 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, instructors are able to upload a zip file to create an assignment from an exported configuration (courses/<:course_id>/assignments/upload_config_files). The uploaded zip file entry names are used to create paths to write files to disk without checking these paths. This vulnerability is fixed in 2.9.1.

Weakness: CWE-23

Which versions are affected by CVE-2026-25057?

It affects 1 product.

Products include Markusproject Markus.

How do I fix CVE-2026-25057?

No fix has been published for CVE-2026-25057 yet. Limit exposure of the affected software until one is available.

Upgrade, and resolve every user-supplied path against an allowed base folder before opening it. More about Path traversal.

Is CVE-2026-25057 being exploited?

There is no known exploitation of CVE-2026-25057 in the wild and no public exploit code.

Public exploit code: 1 proofs of concept on GitHub.

Sources

Also known as GHSA-mccg-p332-252h.