# CVE-2019-12739: Command injection in n/a

> Remote attackers can execute arbitrary code on Nextcloud servers by injecting shell metacharacters into RAR filenames processed by the Extract add-on.

- **Severity:** Critical 9.0 (`CVSS:3.0/AC:L/AV:N/A:H/C:H/I:H/PR:L/S:C/UI:R`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Over the internet
- **Victim action needed:** A user has to click or open something
- **Fix available:** No
- **Published:** 5 Jun 2019
- **Updated:** 4 Aug 2024
- **Also known as:** CVE-2019-5441, GHSA-vpwh-6v3v-q9vw

## What is CVE-2019-12739?

CVE-2019-12739 is a critical command injection vulnerability in n/a, published on 5 Jun 2019. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.

### Official description

lib/Controller/ExtractionController.php in the Extract add-on before 1.2.0 for Nextcloud allows Remote Code Execution via shell metacharacters in a RAR filename via ajax/extractRar.php (nameOfFile and directory parameters).

Weakness: CWE-78 (Improper Neutralization of Special Elements used in an OS Command)

## Which versions are affected by CVE-2019-12739?

It affects 1 product.


Products: Nextcloud Extract.

## How do I fix CVE-2019-12739?

No fix has been published for CVE-2019-12739 yet. Limit exposure of the affected software until one is available.

## Is CVE-2019-12739 being exploited?

There is no known exploitation of CVE-2019-12739 in the wild and no public exploit code.

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2019-12739 and fix it if it is affected.

What it is: CVE-2019-12739 is a critical command injection vulnerability in n/a, published on 5 Jun 2019. Any signed-in user can exploit it over the network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2019-12739 in the wild and no public exploit code.

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-2019-12739/ (Markdown: https://insights.sbomify.com/CVE-2019-12739/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2019-12739
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2019-12739
- OSV: https://osv.dev/vulnerability/CVE-2019-12739

---
From sbomify Insights: https://insights.sbomify.com/CVE-2019-12739/
Summaries are generated and may contain mistakes; the official description above is the record.