# CVE-2021-22600: Linux Kernel Privilege Escalation

> A local attacker can exploit a double free bug in the Linux kernel packet socket implementation to escalate privileges or cause a denial of service.

- **Severity:** Medium 6.6 (`CVSS:3.1/AV:L/AC:H/PR:L/UI:R/S:C/C:L/I:L/A:H`)
- **Exploited in the wild:** Yes, since 11 Apr 2022 (CISA KEV)
- **Login needed:** Any signed-in user
- **Attackable:** Local or same network only
- **Victim action needed:** A user has to click or open something
- **Fix available:** Yes
- **Published:** 26 Jan 2022
- **Updated:** 21 Oct 2025
- **Also known as:** A-213464034, ASB-A-213464034, AZL-8450, DEBIAN-CVE-2021-22600, GHSA-6rrc-7vqp-364c, PUB-A-213464034, UBUNTU-CVE-2021-22600

## What is CVE-2021-22600?

CVE-2021-22600 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 26 Jan 2022. 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

A double free bug in packet_set_ring() in net/packet/af_packet.c can be exploited by a local user through crafted syscalls to escalate privileges or deny service. We recommend upgrading kernel past the effected versions or rebuilding past ec6af094ea28f0f2dda1a6a33b14cd57e36a9755

Weakness: CWE-415 (Double Free)

## Which versions are affected by CVE-2021-22600?

It affects 11 products.


Products: Debian Debian Linux, Linux kernel, Netapp 8300 Firmware, Netapp 8700 Firmware, Netapp A400 Firmware, Netapp C400 Firmware, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware, Netapp H500s Firmware, Netapp H700s Firmware.

## How do I fix CVE-2021-22600?

Upgrade to a fixed version. US federal agencies must fix it by 2 May 2022.

## Is CVE-2021-22600 being exploited?

Yes. Attackers have exploited CVE-2021-22600 in the wild since at least 11 Apr 2022.

Public exploit code:

- https://github.com/sendINUX/CVE-2021-22600__DirtyPagetable (github_poc): https://github.com/sendINUX/CVE-2021-22600__DirtyPagetable
- Proof-Of-Concept to check privileges of af_packet.c for validating the privileges acquired by any hacker upon successful exploitation of CVE-2021-22600 (github_poc): https://github.com/Chinmay1743/af_packet.c

## 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-2021-22600 and fix it if it is affected.

What it is: CVE-2021-22600 is a medium-severity use after free vulnerability in Debian Debian Linux, published on 26 Jan 2022. 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: Yes. Attackers have exploited CVE-2021-22600 in the wild since at least 11 Apr 2022.

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-2021-22600/ (Markdown: https://insights.sbomify.com/CVE-2021-22600/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-22600
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-22600
- OSV: https://osv.dev/vulnerability/CVE-2021-22600

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-22600/
Summaries are generated and may contain mistakes; the official description above is the record.