CVE-2022-1055

A use-after-free vulnerability was found in the tc_new_tfilter function in net/sched/cls_api.c in the Linux kernel. The availability of local, unprivileged user namespaces allows privilege escalation.

The vulnerability in the Linux kernel is shipped in Red Hat Enterprise Linux 8.

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.

On non-containerized deployments of Red Hat Enterprise Linux 8, you can disable user namespaces by setting user.max_user_namespaces to 0:

echo "user.max_user_namespaces=0" > /etc/sysctl.d/userns.conf

sysctl -p /etc/sysctl.d/userns.conf

On containerized deployments, such as Red Hat OpenShift Container Platform, do not use this mitigation as the functionality is needed to be enabled.