Vulnerability · Published Feb 9, 2026 · Assigned by GitHub_M

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

Critical 9.1

In plain English

A critical-severity security flaw in Markus from MarkUsProject. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 46% of all known vulnerabilities). Ready-made attack tooling exists: public proof-of-concept code.

Severity (CVSS 3.1)9.1Critical

Exploit odds (30 days)0.5%top 54.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: none

Attack tooling1Public PoC

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.

Affected products (as reported)

Vendor	Product	Versions
MarkUsProject	Markus	< 2.9.1

Weakness: CWE-23 · Vector: CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H

References

https://github.com/MarkUsProject/Markus/security/advisories/GHSA-mccg-p332-252h x_refsource_CONFIRM
https://github.com/MarkUsProject/Markus/commit/0ca002a1f0071c7a00dbb2ed34fede57323c5dc7 x_refsource_MISC
https://github.com/MarkUsProject/Markus/releases/tag/v2.9.1 x_refsource_MISC