CVE-2023-23454

An out-of-bounds (OOB) read problem was found in cbq_classify in net/sched/sch_cbq.c in the Linux kernel. This issue may allow a local attacker to cause a denial of service due to type confusion. Non-negative numbers could indicate a TC_ACT_SHOT condition rather than valid classification results.

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.

The mitigation is to disable unprivileged 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

It is also possible to prevent the affected code from being loaded by blacklisting the cbq kernel module. For instructions on how to blacklist a kernel module, please see https://access.redhat.com/solutions/41278.