# CVE-2019-20851: Path traversal in n/a

> An attacker can exploit a directory traversal flaw in the Video Preview feature to overwrite arbitrary files on the device.

- **Severity:** Critical 9.1 (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Over the internet
- **Victim action needed:** Not needed
- **Fix available:** No
- **Published:** 19 Jun 2020
- **Updated:** 5 Aug 2024
- **Also known as:** GHSA-hjj4-ch7m-p53m

## What is CVE-2019-20851?

CVE-2019-20851 is a critical path traversal vulnerability in Mattermost Mattermost, published on 19 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.

### Official description

An issue was discovered in Mattermost Mobile Apps before 1.26.0. An attacker can use directory traversal with the Video Preview feature to overwrite arbitrary files on a device.

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

## Which versions are affected by CVE-2019-20851?

It affects 1 product.


Products: Mattermost Mattermost.

## How do I fix CVE-2019-20851?

No fix has been published for CVE-2019-20851 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-20851 being exploited?

There is no known exploitation of CVE-2019-20851 in the wild and no public exploit code.

## Other vulnerabilities in Mattermost Mattermost

- [CVE-2024-39274](https://insights.sbomify.com/CVE-2024-39274/): Malicious remote can add users to arbitrary teams and channels (high 8.7)
- [CVE-2024-39777](https://insights.sbomify.com/CVE-2024-39777/): Malicious remote can invite itself to an arbitrary local channel (high 8.7)
- [CVE-2024-39830](https://insights.sbomify.com/CVE-2024-39830/): Timing attack during remote cluster token comparison when shared channels are enabled (high 8.1)
- [CVE-2023-3615](https://insights.sbomify.com/CVE-2023-3615/): Lack of server certificate validation in websockets connection (high 8.1)
- [CVE-2020-13891](https://insights.sbomify.com/CVE-2020-13891/): Information disclosure in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-20851 and fix it if it is affected.

What it is: CVE-2019-20851 is a critical path traversal vulnerability in Mattermost Mattermost, published on 19 Jun 2020. An attacker can exploit it over the internet without logging in, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2019-20851 in the wild and no public exploit code.

Affected product: Mattermost Mattermost. 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-2019-20851/ (Markdown: https://insights.sbomify.com/CVE-2019-20851/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-20851
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-20851
- OSV: https://osv.dev/vulnerability/CVE-2019-20851

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-20851/
Summaries are generated and may contain mistakes; the official description above is the record.