# CVE-2021-4197: Privilege escalation in kernel

> A local attacker can exploit a flaw in the Linux kernel's cgroups subsystem to escalate privileges or crash the system.

- **Severity:** High 7.8 (`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/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:** 23 Mar 2022
- **Updated:** 3 Aug 2024
- **Also known as:** AZL-9141, DEBIAN-CVE-2021-4197, UBUNTU-CVE-2021-4197

## What is CVE-2021-4197?

CVE-2021-4197 is a high-severity vulnerability in Debian Debian Linux, published on 23 Mar 2022. It can only be exploited from the same machine or local network, with no action from the victim.

### Official description

An unprivileged write to the file handler flaw in the Linux kernel's control groups and namespaces subsystem was found in the way users have access to some less privileged process that are controlled by cgroups and have higher privileged parent process. It is actually both for cgroup2 and cgroup1 versions of control groups. A local user could use this flaw to crash the system or escalate their privileges on the system.

Weakness: CWE-287 (Improper Authentication)

## Which versions are affected by CVE-2021-4197?

It affects 9 products.


Products: Broadcom Brocade Fabric Operating System Firmware, Debian Debian Linux, Linux kernel, Netapp H300s Firmware, Netapp H410c Firmware, Netapp H410s Firmware, Netapp H500s Firmware, Netapp H700s Firmware, Oracle Communications Cloud Native Core Binding Support Function.

## How do I fix CVE-2021-4197?

Apply the vendor's patch.

## Is CVE-2021-4197 being exploited?

There is no known exploitation of CVE-2021-4197 in the wild and no public exploit code.

## Other vulnerabilities in Debian Debian Linux

- [CVE-2023-27534](https://insights.sbomify.com/CVE-2023-27534/): Path traversal in https://github.com/curl/curl (high 8.8)
- [CVE-2023-27538](https://insights.sbomify.com/CVE-2023-27538/): Auth bypass in https://github.com/curl/curl (high 7.7)
- [CVE-2021-27218](https://insights.sbomify.com/CVE-2021-27218/): Integer overflow in n/a (high 7.5)
- [CVE-2021-27219](https://insights.sbomify.com/CVE-2021-27219/): Integer overflow in n/a (high 7.5)
- [CVE-2019-19044](https://insights.sbomify.com/CVE-2019-19044/): Denial of service in n/a (high 7.5)

## Fix prompt for AI coding agents

```text
Check this codebase for CVE-2021-4197 and fix it if it is affected.

What it is: CVE-2021-4197 is a high-severity vulnerability in Debian Debian Linux, published on 23 Mar 2022. 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-2021-4197 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-2021-4197/ (Markdown: https://insights.sbomify.com/CVE-2021-4197/index.md)
```

## Sources

- CVE record: https://www.cve.org/CVERecord?id=CVE-2021-4197
- NVD: https://nvd.nist.gov/vuln/detail/CVE-2021-4197
- OSV: https://osv.dev/vulnerability/CVE-2021-4197

---
From sbomify Insights: https://insights.sbomify.com/CVE-2021-4197/
Summaries are generated and may contain mistakes; the official description above is the record.