# CVE-2017-18241: Null dereference in n/a

> Local users can cause a kernel panic and denial of service via a NULL pointer dereference in the F2FS filesystem when using the noflush_merge option.

- **Severity:** Medium 5.5 (`CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Mar 2018
- **Updated:** 5 Aug 2024
- **Also known as:** DEBIAN-CVE-2017-18241, GHSA-fmfp-q8w9-qgxv, UBUNTU-CVE-2017-18241

## What is CVE-2017-18241?

CVE-2017-18241 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 21 Mar 2018. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

fs/f2fs/segment.c in the Linux kernel before 4.13 allows local users to cause a denial of service (NULL pointer dereference and panic) by using a noflush_merge option that triggers a NULL value for a flush_cmd_control data structure.

Weakness: CWE-476 (NULL Pointer Dereference)

## Which versions are affected by CVE-2017-18241?

It affects 3 products.


Products: Canonical Ubuntu Linux, Debian Debian Linux, Linux kernel.

## How do I fix CVE-2017-18241?

Upgrade to a fixed version.

## Is CVE-2017-18241 being exploited?

There is no known exploitation of CVE-2017-18241 in the wild and no public exploit code.

## Other vulnerabilities in Canonical Ubuntu Linux

- [CVE-2020-11651](https://insights.sbomify.com/CVE-2020-11651/): SaltStack Salt Authentication Bypass (critical 9.8, exploited in the wild)
- [CVE-2020-7247](https://insights.sbomify.com/CVE-2020-7247/): OpenSMTPD Remote Code Execution (critical 9.8, exploited in the wild)
- [CVE-2019-16928](https://insights.sbomify.com/CVE-2019-16928/): Exim Out-of-bounds Write (critical 9.8, exploited in the wild)
- [CVE-2018-6789](https://insights.sbomify.com/CVE-2018-6789/): Exim Buffer Overflow (critical 9.8, exploited in the wild)
- [CVE-2015-2590](https://insights.sbomify.com/CVE-2015-2590/): Oracle Java SE and Java SE Embedded Remote Code Execution (critical 9.8, exploited in the wild)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2017-18241 and fix it if it is affected.

What it is: CVE-2017-18241 is a medium-severity vulnerability in Canonical Ubuntu Linux, published on 21 Mar 2018. It can only be exploited from the same machine or local network, with no action from the victim.
Exploitation: There is no known exploitation of CVE-2017-18241 in the wild and no public exploit code.

Affected product: Canonical Ubuntu 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-2017-18241/ (Markdown: https://insights.sbomify.com/CVE-2017-18241/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2017-18241
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2017-18241
- OSV: https://osv.dev/vulnerability/CVE-2017-18241

---
From sbomify Insights: https://insights.sbomify.com/CVE-2017-18241/
Summaries are generated and may contain mistakes; the official description above is the record.