CVE-2023-23455

A denial of service flaw was found in atm_tc_enqueue in net/sched/sch_atm.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.

Mitigation

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