A vulnerability was found in the Linux kernel’s cgroup_release_agent_write
in the kernel/cgroup/cgroup-v1.c function. This flaw, under certain
circumstances, allows the use of the cgroups v1 release_agent feature to
escalate privileges and bypass the namespace isolation unexpectedly.

Yiqi Sun and Kevin Wang discovered that the cgroups implementation in the
Linux kernel did not properly restrict access to the cgroups v1
release_agent feature. A local attacker could use this to gain
administrative privileges.