CVE-2021-4197: High severity linux kernel vulnerability
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.
Other sources
In cgroups (control groups) functionality of Linux Kernel found potential security weakness that may allow scenarios where a less privileged process tricks a more privileged one into writing into a fd that it created. This could lead to local escalation of privilege for the containers or other processes that uses cgroups in such a way. User interaction is not needed for exploitation.
Reference and upstream patch: https://lore.kernel.org/lkml/20211209214707.805617-1-tj@kernel.org/T/
— Red Hat
Affected Software
Remediation
Information
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2021-4197?
CVE-2021-4197 has a high severity rating due to the potential for unprivileged users to write to file handlers controlled by cgroups.
What versions of the Linux kernel are affected by CVE-2021-4197?
CVE-2021-4197 affects Linux kernel versions up to 4.18.0-372.9.1 and various versions within the 4.x series up to 5.x.
How do I fix CVE-2021-4197?
To fix CVE-2021-4197, update your Linux kernel to the specified remedied versions for your distribution as indicated in the security advisories.
Can CVE-2021-4197 be exploited remotely?
CVE-2021-4197 requires local access to exploit, which means it cannot be directly exploited remotely.
What are the potential impacts of CVE-2021-4197?
The potential impacts of CVE-2021-4197 include unauthorized access to file handlers and potential privilege escalation for unprivileged processes.