CVE-2021-4197

Publication date 31 December 2021

Last updated 10 September 2026

Ubuntu priority

High

Why this priority?

Cvss 3 Severity Score

7.8 · High

Score breakdown

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.

From the Ubuntu Security Team

Eric Biederman discovered that the cgroup process migration implementation in the Linux kernel did not perform permission checks correctly in some situations. A local attacker could possibly use this to gain administrative privileges.

Why is this CVE high priority?

See ubuntu cvss score

Learn more about Ubuntu priority

Status

Package Ubuntu Release Status
linux-gke 26.04 LTS resolute
Not affected
25.10 questing Not in release
25.04 plucky Not in release
24.10 oracular Not in release
24.04 LTS noble
Not affected
23.10 mantic Not in release
23.04 lunar Not in release
22.10 kinetic Not in release
22.04 LTS jammy
Not affected
21.10 impish Not in release
21.04 hirsute Not in release
20.04 LTS focal
Fixed 5.4.0-1074.79
18.04 LTS bionic Not in release
16.04 LTS xenial Ignored end of standard support
14.04 LTS trusty Not in release
linux-xilinx 26.04 LTS resolute Not in release
25.10 questing Not in release
25.04 plucky
Not affected
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-nvidia-bos 26.04 LTS resolute
Not affected
25.10 questing Not in release
24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-nvidia-7.0 26.04 LTS resolute Not in release
25.10 questing Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-hwe-7.0 26.04 LTS resolute Not in release
25.10 questing Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oem-7.0 26.04 LTS resolute
Not affected
25.10 questing Not in release
24.04 LTS noble Not in release
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-aws-7.0 26.04 LTS resolute Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-riscv-7.0 26.04 LTS resolute Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-7.0 26.04 LTS resolute Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-azure-fde-7.0 26.04 LTS resolute Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-gcp-7.0 26.04 LTS resolute Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux-oracle-7.0 26.04 LTS resolute Not in release
24.04 LTS noble
Not affected
22.04 LTS jammy Not in release
20.04 LTS focal Not in release
18.04 LTS bionic Not in release
16.04 LTS xenial Not in release
14.04 LTS trusty Not in release
linux 26.04 LTS resolute
Not affected
25.10 questing
Not affected
25.04 plucky
Not affected
24.10 oracular
Not affected
24.04 LTS noble
Not affected
23.10 mantic
Not affected
23.04 lunar
Not affected
22.10 kinetic
Not affected
22.04 LTS jammy
Not affected
21.10 impish
Fixed 5.13.0-37.42
21.04 hirsute Ignored end of life
20.04 LTS focal
Fixed 5.4.0-117.132
18.04 LTS bionic
Fixed 4.15.0-189.200
16.04 LTS xenial
Fixed 4.4.0-229.263
14.04 LTS trusty
Not affected
linux-allwinner 26.04 LTS resolute Not in release
25.10 questing Not in release
25.04 plucky Not in release
24.10 oracular Not in release
24.04 LTS noble Not in release
23.10 mantic Not in release
23.04 lunar
Not affected
22.10 kinetic