# CVE-2021-37159: Use after free in n/a

> A use-after-free vulnerability in the Linux kernel's HSO driver allows local attackers to potentially execute arbitrary code or escalate privileges.

- **Severity:** Medium 6.4 (`CVSS:3.1/AV:P/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H`)
- **Exploited in the wild:** Not known
- **Login needed:** Not needed
- **Attackable:** Local or same network only
- **Victim action needed:** Not needed
- **Fix available:** Yes
- **Published:** 21 Jul 2021
- **Updated:** 8 Oct 2026
- **Also known as:** A-195082947, AZL-6578, DEBIAN-CVE-2021-37159, GHSA-jh5h-88qq-m547, PUB-A-195082947, UBUNTU-CVE-2021-37159

## What is CVE-2021-37159?

CVE-2021-37159 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 21 Jul 2021. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

hso_free_net_device in drivers/net/usb/hso.c in the Linux kernel through 5.13.4 calls unregister_netdev without checking for the NETREG_REGISTERED state, leading to a use-after-free and a double free.

Weakness: CWE-416 (Use After Free), CWE-415 (Double Free)

## Which versions are affected by CVE-2021-37159?

It affects 5 products.


Products: Debian Debian Linux, Linux kernel, Oracle Communications Cloud Native Core Binding Support Function, Oracle Communications Cloud Native Core Network Exposure Function, Oracle Communications Cloud Native Core Policy.

## How do I fix CVE-2021-37159?

Apply the vendor's patch.

## Is CVE-2021-37159 being exploited?

There is no known exploitation of CVE-2021-37159 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-2021-37159 and fix it if it is affected.

What it is: CVE-2021-37159 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 21 Jul 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-2021-37159 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-2021-37159/ (Markdown: https://insights.sbomify.com/CVE-2021-37159/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-37159
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-37159
- OSV: https://osv.dev/vulnerability/CVE-2021-37159

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-37159/
Summaries are generated and may contain mistakes; the official description above is the record.