In FreeBSD 12.1-STABLE before r357490, 12.1-RELEASE before 12.1-RELEASE-p3, 11.3-STABLE before r357489, and 11.3-RELEASE before 11.3-RELEASE-p7, incorrect use of a user-controlled pointer in the epair virtual network module allowed vnet jailed privileged users to panic the host system and potentially execute arbitrary code in the kernel.