# CVE-2017-14121: Null dereference in n/a

> A crafted RAR archive triggers a NULL pointer dereference in the unrar library, causing a denial of service.

- **Severity:** Medium 5.5 (`CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 3 Sep 2017
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2017-14121, GHSA-r9qm-gm5q-gx7p, UBUNTU-CVE-2017-14121

## What is CVE-2017-14121?

CVE-2017-14121 is a medium-severity vulnerability in Debian Debian Linux, published on 3 Sep 2017. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.

### Official description

The DecodeNumber function in unrarlib.c in unrar 0.0.1 (aka unrar-free or unrar-gpl) suffers from a NULL pointer dereference flaw triggered by a crafted RAR archive. NOTE: this may be the same as one of the several test cases in the CVE-2017-11189 references.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2017-14121?

It affects 2 products.


Products: Debian Debian Linux, Rarlab Unrar.

## How do I fix CVE-2017-14121?

Apply the vendor's patch.

## Is CVE-2017-14121 being exploited?

There is no known exploitation of CVE-2017-14121 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2015-3306](https://insights.sbomify.com/CVE-2015-3306/): ProFTPD Improper Access Control (critical 10.0, exploited in the wild)
- [CVE-2025-49113](https://insights.sbomify.com/CVE-2025-49113/): RoundCube Webmail Deserialization of Untrusted Data (critical 9.9, exploited in the wild)
- [CVE-2026-24061](https://insights.sbomify.com/CVE-2026-24061/): GNU InetUtils Argument Injection (critical 9.8, exploited in the wild)
- [CVE-2025-39682](https://insights.sbomify.com/CVE-2025-39682/): Linux Kernel Improper Check for Unusual or Exceptional Conditions (critical 9.8, exploited in the wild)
- [CVE-2024-9680](https://insights.sbomify.com/CVE-2024-9680/): Mozilla Firefox Use-After-Free (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-14121 and fix it if it is affected.

What it is: CVE-2017-14121 is a medium-severity vulnerability in Debian Debian Linux, published on 3 Sep 2017. It can only be exploited from the same machine or local network, and only if a user opens a file or follows a link.
Exploitation: There is no known exploitation of CVE-2017-14121 in the wild and no public exploit code.

Affected product: Debian Debian Linux. 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-2017-14121/ (Markdown: https://insights.sbomify.com/CVE-2017-14121/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-14121
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-14121
- OSV: https://osv.dev/vulnerability/CVE-2017-14121

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-14121/
Summaries are generated and may contain mistakes; the official description above is the record.