A use-after-free write vulnerability was identified within the netfilter subsystem which can be exploited to achieve privilege escalation to root. In order to trigger the issue it requires the ability to create user/net namespaces.
The author included a proof-of-concept code in his article. The kernel repository already includes an update. Until this is available for all systems it usually takes quite some time. Red Hat assigned CVE-2022-1966 to the bug, but as noted on oss-security the same issue also received CVE-2022-32250. Red Hat’s CVE page now lists CVE-2022-1966 as rejected, a duplicate of CVE-2022-32250, which is the ID to search for.
As a mitigation user namespaces can be disabled. These privileges are usually only required on containerized systems.
echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf
sysctl -p /etc/sysctl.d/userns.conf