# CVE-2021-42375: Denial of service in busybox

> Attackers can cause denial of service in BusyBox ash by crafting specific shell commands that exploit incorrect character handling.

- **Severity:** Medium 5.5 (`CVSS:3.1/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:** 15 Nov 2021
- **Updated:** 23 Apr 2025
- **Also known as:** ALPINE-CVE-2021-42375, DEBIAN-CVE-2021-42375, GHSA-h7xx-2pfg-qqhm

## What is CVE-2021-42375?

CVE-2021-42375 is a medium-severity denial of service vulnerability in Fedoraproject Fedora, published on 15 Nov 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An incorrect handling of a special element in Busybox's ash applet leads to denial of service when processing a crafted shell command, due to the shell mistaking specific characters for reserved characters. This may be used for DoS under rare conditions of filtered command input.

Weakness: CWE-159 (Improper Handling of Invalid Use of Special Elements)

## Which versions are affected by CVE-2021-42375?

It affects 12 products.


Products: Busybox Busybox, Fedoraproject Fedora, Netapp Cloud Backup, Netapp H300e Firmware, Netapp H300s Firmware, Netapp H410s Firmware, Netapp H500e Firmware, Netapp H500s Firmware, Netapp H700e Firmware, Netapp H700s Firmware, Netapp Hci Management Node, Netapp Solidfire.

## How do I fix CVE-2021-42375?

Apply the vendor's patch.

## Is CVE-2021-42375 being exploited?

There is no known exploitation of CVE-2021-42375 in the wild and no public exploit code.

## Other vulnerabilities in Fedoraproject Fedora

- [CVE-2022-48174](https://insights.sbomify.com/CVE-2022-48174/): Memory corruption in n/a (critical 9.8)
- [CVE-2021-42377](https://insights.sbomify.com/CVE-2021-42377/): Memory corruption in busybox (critical 9.8)
- [CVE-2016-2148](https://insights.sbomify.com/CVE-2016-2148/): Memory corruption in n/a (critical 9.8)
- [CVE-2022-28391](https://insights.sbomify.com/CVE-2022-28391/): Command injection in n/a (high 8.8)
- [CVE-2017-16544](https://insights.sbomify.com/CVE-2017-16544/): Code injection in n/a (high 8.8)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-42375 and fix it if it is affected.

What it is: CVE-2021-42375 is a medium-severity denial of service vulnerability in Fedoraproject Fedora, published on 15 Nov 2021. 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-2021-42375 in the wild and no public exploit code.

Affected product: Fedoraproject Fedora. 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-2021-42375/ (Markdown: https://insights.sbomify.com/CVE-2021-42375/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-42375
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-42375
- OSV: https://osv.dev/vulnerability/CVE-2021-42375

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-42375/
Summaries are generated and may contain mistakes; the official description above is the record.