# CVE-2020-8181: File upload in Nextcloud Contact

> A missing file type check in Nextcloud Contacts allows malicious users to upload arbitrary files as avatars, potentially leading to code execution.

- **Severity:** Medium 4.3 (`CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:L/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:** 10 Jul 2020
- **Updated:** 4 Aug 2024
- **Also known as:** GHSA-wgmx-fv9q-wpfx

## What is CVE-2020-8181?

CVE-2020-8181 is a medium-severity vulnerability in Nextcloud Contact, published on 10 Jul 2020. Any signed-in user can exploit it over the network, with no action from the victim.

### Official description

A missing file type check in Nextcloud Contacts 3.2.0 allowed a malicious user to upload any file as avatars.

Weakness: CWE-434 (Unrestricted Upload of File with Dangerous Type), CWE-840

## Which versions are affected by CVE-2020-8181?

It affects 1 product.


Products: Nextcloud Contacts.

## How do I fix CVE-2020-8181?

No fix has been published for CVE-2020-8181 yet. Limit exposure of the affected software until one is available.

## Is CVE-2020-8181 being exploited?

There is no known exploitation of CVE-2020-8181 in the wild and no public exploit code.

## Other vulnerabilities in Nextcloud Contact

- [CVE-2021-39221](https://insights.sbomify.com/CVE-2021-39221/): XSS in Contacts (medium 6.4)
- [CVE-2020-8280](https://insights.sbomify.com/CVE-2020-8280/): Cross-site scripting in Nextcloud Contacts (medium 5.4)
- [CVE-2020-8281](https://insights.sbomify.com/CVE-2020-8281/): Cross-site scripting in Nextcloud Contacts (medium 5.4)
- [CVE-2018-3764](https://insights.sbomify.com/CVE-2018-3764/): Cross-site scripting in Nextcloud Contacts application (medium 4.8)
- [CVE-2025-66554](https://insights.sbomify.com/CVE-2025-66554/): Nextcloud Contacts vulnerable to Stored XSS in contacts app via organisation and title field (low 3.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2020-8181 and fix it if it is affected.

What it is: CVE-2020-8181 is a medium-severity vulnerability in Nextcloud Contact, published on 10 Jul 2020. Any signed-in user can exploit it over the network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2020-8181 in the wild and no public exploit code.

Affected product: Nextcloud Contact. 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-2020-8181/ (Markdown: https://insights.sbomify.com/CVE-2020-8181/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2020-8181
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2020-8181
- OSV: https://osv.dev/vulnerability/CVE-2020-8181

---
From sbomify Insights: https://insights.sbomify.com/CVE-2020-8181/
Summaries are generated and may contain mistakes; the official description above is the record.