CVE-2026-72254netfilter: nft_fib: reject fib expression on the netdev egress hook

Official description

In the Linux kernel, the following vulnerability has been resolved: netfilter: nft_fib: reject fib expression on the netdev egress hook A fib expression in a netdev egress base chain dereferences nft_in(pkt), NULL on the transmit path, causing a NULL pointer dereference at eval. nft_fib_validate() masks the hook with NF_INET_* values, but netdev hook numbers are a separate enum that aliases them (NF_NETDEV_EGRESS == NF_INET_LOCAL_IN), so an egress chain passes validation and then faults. Add nft_fib_netdev_validate() that limits each result/flag to the netdev hook where the device it reads exists: the input-device cases (OIF, OIFNAME, ADDRTYPE with F_IIF) to ingress, the output-device case (ADDRTYPE with F_OIF) to egress, ADDRTYPE with no device flag to both. Also restrict nft_fib_validate() to NFPROTO_IPV4/IPV6/INET so its NF_INET_* masks are not applied to another family's hooks.

Affected packages & fixed versions

Affected products (as reported)

References

• https://git.kernel.org/stable/c/1258a6da042c0c283dcf5c581acb318db29c760a
• https://git.kernel.org/stable/c/4fee43759b489559a491f7c95f9bfa7a1d0c7a10
• https://git.kernel.org/stable/c/568931f26af4727a51e8521f72efbc78d3b82410
• https://git.kernel.org/stable/c/d01c913febead04a01a5f3a6374d1f45504dc523
• https://git.kernel.org/stable/c/f68305267ebda7e839b5e8f77e8d77535a3d5a0f
• https://git.kernel.org/stable/c/d07955dd34ecae17d35d8c7d0a273a3fba653a8c