# CVE-2021-21250: Post-Auth External Entity Expansion (XXE)

> Authenticated attackers can exploit XML external entity injection in OneDev to read arbitrary files from the server filesystem.

- **Severity:** High 7.7 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:N/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-9pph-8gfc-6w2r

## What is CVE-2021-21250?

CVE-2021-21250 is a high-severity 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 vulnerability which may lead to arbitrary file read. When BuildSpec is provided in XML format, the spec is processed by XmlBuildSpecMigrator.migrate(buildSpecString); which processes the XML document without preventing the expansion of external entities. These entities can be configured to read arbitrary files from the file system and dump their contents in the final XML document to be migrated. If the files are dumped in properties included in the YAML file, it will be possible for an attacker to read them. If not, it is possible for an attacker to exfiltrate the contents of these files Out Of Band. This issue was addressed in 4.0.3 by ignoring ENTITY instructions in xml file.

Weakness: CWE-538 (Insertion of Sensitive Information into Externally-Accessible File or Directory)

## Which versions are affected by CVE-2021-21250?

It affects 1 product.


Products: Onedev Project Onedev.

## How do I fix CVE-2021-21250?

No fix has been published for CVE-2021-21250 yet. Limit exposure of the affected software until one is available.

## Is CVE-2021-21250 being exploited?

There is no known exploitation of CVE-2021-21250 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-2021-21250 and fix it if it is affected.

What it is: CVE-2021-21250 is a high-severity 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-2021-21250 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-2021-21250/ (Markdown: https://insights.sbomify.com/CVE-2021-21250/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-21250
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-21250
- OSV: https://osv.dev/vulnerability/CVE-2021-21250

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-21250/
Summaries are generated and may contain mistakes; the official description above is the record.