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

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

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:H/UI:N/S:C/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** An administrator
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 9 Feb 2026
- **Updated:** 10 Feb 2026
- **Also known as:** GHSA-mccg-p332-252h

## 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 (Relative Path Traversal)

## Which versions are affected by CVE-2026-25057?

It affects 1 product.


Products: 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.

## 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:

- PoC for Zip Slip in MarkUs Assignment Configuration Uploads (github_poc): https://github.com/ustr/CVE-2026-25057

## Other vulnerabilities in MarkUsProject Markus

- [CVE-2026-28405](https://insights.sbomify.com/CVE-2026-28405/): MarkUs: Stored XSS in Submission HTML Preview Enables Instructor-Context Actions (high 8.0)
- [CVE-2024-51499](https://insights.sbomify.com/CVE-2024-51499/): MarkUs Arbitrary File Write leading up to remote code execution (student accounts) (high 7.1)
- [CVE-2024-51743](https://insights.sbomify.com/CVE-2024-51743/): Arbitrary File Write leading up to remote code execution (instructor accounts) (high 7.1)
- [CVE-2026-25962](https://insights.sbomify.com/CVE-2026-25962/): MarkUs: Zip bomb in config upload enables DoS (medium 6.5)
- [CVE-2026-24900](https://insights.sbomify.com/CVE-2026-24900/): MarkUs has a submission-view IDOR exposes all student submissions (medium 6.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2026-25057 and fix it if it is affected.

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

Affected product: MarkUsProject Markus. No package-level version data is available, so check the vendor advisory linked from the reference page.

Task:
1. Search the dependency manifests and lockfiles (for example package.json, package-lock.json, requirements.txt, poetry.lock, uv.lock, pom.xml, build.gradle, go.mod, Cargo.lock, Gemfile.lock) and any Dockerfiles for the affected packages, including transitive dependencies.
2. If an affected version is in use, upgrade it to the fixed version for its release line with the project's package manager, so the lockfile is regenerated. Prefer the smallest upgrade that fixes it.
3. If there is no fix, or the upgrade would break the build, do not guess: explain the risk and the safest workaround instead.
4. Run the tests and summarise what changed and why.
5. If nothing in the project is affected, say so and change nothing.

Reference: https://insights.sbomify.com/CVE-2026-25057/ (Markdown: https://insights.sbomify.com/CVE-2026-25057/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-25057
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25057
- OSV: https://osv.dev/vulnerability/CVE-2026-25057

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-25057/
Summaries are generated and may contain mistakes; the official description above is the record.