CVE-2021-4197
kernel: cgroup: Use open-time creds and namespace for migration perm checks
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · September 12, 2021
Updated · June 28, 2026
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.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
The mitigation not known. However, for the default configuration of the Red Hat Enterprise Linux it is not possible to trigger this vulnerability: if control groups (cgroups) not being used or being used with the default configuration or being used some other configuration where for example similar privileges for all processes (both for parent and for child processes), then no way to trigger this vulnerability.
CVSS / CWE
CVSS 3.1 · 6.3CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N
CWE-287 · Improper Authentication