# CVE-2026-25962: MarkUs: Zip bomb in config upload enables DoS

> Attackers can cause denial of service by uploading malicious zip bombs to the MarkUs web application due to missing extraction limits.

- **Severity:** Medium 6.5 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 6 Mar 2026
- **Updated:** 6 Mar 2026
- **Also known as:** GHSA-x8xv-j7fc-65x5

## What is CVE-2026-25962?

CVE-2026-25962 is a medium-severity denial of service vulnerability in MarkUsProject Markus, published on 6 Mar 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 version 2.9.4, MarkUs currently extracts zip files without any size or entry-count limits. For example, instructors can upload a zip file to provide an assignment configuration; students can upload a zip file for an assignment submission and indicate its contents should be extracted. This issue has been patched in version 2.9.4.

Weakness: CWE-409 (Improper Handling of Highly Compressed Data (Data Amplification))

## Which versions are affected by CVE-2026-25962?

It affects 1 product.


Products: Markusproject Markus.

## How do I fix CVE-2026-25962?

No fix has been published for CVE-2026-25962 yet. Limit exposure of the affected software until one is available.

## Is CVE-2026-25962 being exploited?

There is no known exploitation of CVE-2026-25962 in the wild and no public exploit code.

## Other vulnerabilities in MarkUsProject Markus

- [CVE-2026-25057](https://insights.sbomify.com/CVE-2026-25057/): Zip Slip in MarkUs config upload allowing RCE (critical 9.1)
- [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-2026-24900](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-2026-25962 and fix it if it is affected.

What it is: CVE-2026-25962 is a medium-severity denial of service vulnerability in MarkUsProject Markus, published on 6 Mar 2026. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2026-25962 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-2026-25962/ (Markdown: https://insights.sbomify.com/CVE-2026-25962/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2026-25962
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2026-25962
- OSV: https://osv.dev/vulnerability/CVE-2026-25962

---
From sbomify Insights: https://insights.sbomify.com/CVE-2026-25962/
Summaries are generated and may contain mistakes; the official description above is the record.