A flaw was found in the Linux Kernel. The tun/tap sockets have their socket UID hardcoded to 0 due to a type confusion in their initialization function. While it will be often correct, as tuntap devices require CAP_NET_ADMIN, it may not always be the case, e.g., a non-root user only having that capability. This would make tun/tap sockets being incorrectly treated in filtering/routing decisions, possibly bypassing network filters.