# CVE-2021-21251: ZipSlip Arbitrary File Upload

> Attackers with valid job tokens can exploit a zip slip vulnerability in OneDev to write arbitrary files, potentially leading to code execution.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N`)
- **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:** 15 Jan 2021
- **Updated:** 3 Aug 2024
- **Also known as:** GHSA-2w6j-wc8c-9mq2

## What is CVE-2021-21251?

CVE-2021-21251 is a high-severity path traversal vulnerability in theonedev onedev, published on 15 Jan 2021. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

OneDev is an all-in-one devops platform. In OneDev before version 4.0.3 there is a critical "zip slip" vulnerability. This issue may lead to arbitrary file write. The KubernetesResource REST endpoint untars user controlled data from the request body using TarUtils. TarUtils is a custom library method leveraging Apache Commons Compress. During the untar process, there are no checks in place to prevent an untarred file from traversing the file system and overriding an existing file. For a successful exploitation, the attacker requires a valid __JobToken__ which may not be possible to get without using any of the other reported vulnerabilities. But this should be considered a vulnerability in `io.onedev.commons.utils.TarUtils` since it lives in a different artifact and can affect other projects using it. This issue was addressed in 4.0.3 by validating paths in tar archive to only allow them to be in specified folder when extracted.

Weakness: CWE-22 (Improper Limitation of a Pathname to a Restricted Directory)

## Which versions are affected by CVE-2021-21251?

It affects 1 product.


Products: Onedev Project Onedev.

## How do I fix CVE-2021-21251?

No fix has been published for CVE-2021-21251 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21251 being exploited?

There is no known exploitation of CVE-2021-21251 in the wild and no public exploit code.

## Other vulnerabilities in theonedev onedev

- [CVE-2021-21242](https://insights.sbomify.com/CVE-2021-21242/): Pre-Auth Unsafe Deserialization on AttachmentUploadServet (critical 10.0)
- [CVE-2021-21243](https://insights.sbomify.com/CVE-2021-21243/): Pre-Auth Unsafe Deserialization on KubernetesResource (critical 10.0)
- [CVE-2021-21244](https://insights.sbomify.com/CVE-2021-21244/): Pre-Auth SSTI via Bean validation message tampering (critical 10.0)
- [CVE-2021-21245](https://insights.sbomify.com/CVE-2021-21245/): Pre-Auth Arbitrary File Upload (critical 10.0)
- [CVE-2022-39206](https://insights.sbomify.com/CVE-2022-39206/): CI/CD Docker Escape in OneDev (critical 9.9)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-21251 and fix it if it is affected.

What it is: CVE-2021-21251 is a high-severity path traversal vulnerability in theonedev onedev, published on 15 Jan 2021. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2021-21251 in the wild and no public exploit code.

Affected product: theonedev onedev. 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-2021-21251/ (Markdown: https://insights.sbomify.com/CVE-2021-21251/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21251
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21251
- OSV: https://osv.dev/vulnerability/CVE-2021-21251

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21251/
Summaries are generated and may contain mistakes; the official description above is the record.