# CVE-2020-21861: File upload in n/a

> Attackers can execute arbitrary PHP code by uploading malicious files to the DuxCMS admin upload endpoint.

- **Severity:** High 8.8 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/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 Jul 2023
- **Updated:** 21 Nov 2024
- **Also known as:** GHSA-cxvj-gmrx-gjv8

## What is CVE-2020-21861?

CVE-2020-21861 is a high-severity vulnerability in n/a, published on 6 Jul 2023. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

File upload vulnerability in DuxCMS 2.1 allows attackers to execute arbitrary php code via duxcms/AdminUpload/upload.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type)

## Which versions are affected by CVE-2020-21861?

It affects 1 product.


Products: Duxcms Project Duxcms.

## How do I fix CVE-2020-21861?

No fix has been published for CVE-2020-21861 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-21861 being exploited?

It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-21861 exists.

## Other vulnerabilities in n/a

- [CVE-2021-3242](https://insights.sbomify.com/CVE-2021-3242/): SQL injection in n/a (critical 9.8)
- [CVE-2020-21862](https://insights.sbomify.com/CVE-2020-21862/): Path traversal in n/a (high 8.1)
- [CVE-2020-21881](https://insights.sbomify.com/CVE-2020-21881/): Cross-site request forgery in n/a (medium 6.5)
- [CVE-2020-36763](https://insights.sbomify.com/CVE-2020-36763/): Cross-site scripting in n/a (medium 5.4)
- [CVE-2020-36610](https://insights.sbomify.com/CVE-2020-36610/): annyshow DuxCMS cross-site request forgery (medium 4.3)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-21861 and fix it if it is affected.

What it is: CVE-2020-21861 is a high-severity vulnerability in n/a, published on 6 Jul 2023. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: It is not confirmed as exploited in the wild, but public exploit code for CVE-2020-21861 exists.

Affected product: n/a. 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-2020-21861/ (Markdown: https://insights.sbomify.com/CVE-2020-21861/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-21861
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-21861
- OSV: https://osv.dev/vulnerability/CVE-2020-21861

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-21861/
Summaries are generated and may contain mistakes; the official description above is the record.