CVE-2023-54200

A moderate use-after-free flaw was found in the Linux kernel's netfilter/nf_tables subsystem in Red Hat Enterprise Linux 8 (kernel and kernel-rt, across its update streams) and the Red Hat Enterprise Linux 9.0 and 9.2 update streams. When a virtual Ethernet (veth) device is released, the veth release callback also queues the peer network namespace's device for removal; if that peer network namespace is itself being torn down, the device memory can already be freed when the nf_tables pre_exit hook later unregisters the netdev hooks, resulting in a slab use-after-free during network namespace cleanup. A local attacker with the high privileges needed to configure network namespaces, veth devices, and nftables netdev hooks could exploit this flaw during namespace teardown to crash the kernel, resulting in a denial of service. Red Hat rates this flaw Moderate rather than the upstream CVEORG Important severity because exploitation requires a highly privileged local attacker, the attack complexity is high, and the practical consequence is limited to system availability. The fix for the affected Red Hat Enterprise Linux 8 and 9 streams is currently deferred to a future maintenance update, so the residual risk remains a local, privilege-gated denial of service triggered during network namespace teardown. Red Hat Enterprise Linux 6 and 7, the later Red Hat Enterprise Linux 9 update streams (9.4 onward), Red Hat Enterprise Linux 10, and Red Hat In-Vehicle OS are not affected because the vulnerable code is not present in those kernels.