{"id":"CVE-2026-64572","published":"2026-08-05T08:16:36.927","lastModified":"2026-08-05T08:16:36.927","description":"In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: fib: free fib_alias with kfree_rcu() on insert error path\n\nfib_table_insert() publishes new_fa into the leaf's fa_list with\nfib_insert_alias() before calling the fib entry notifiers. When a\nnotifier fails, the error path removes new_fa with fib_remove_alias()\n(hlist_del_rcu) and frees it right away with kmem_cache_free().\n\nfib_table_lookup() walks that list under rcu_read_lock() only, so a\nconcurrent lookup that already reached new_fa keeps reading it after the\nfree:\n\n BUG: KASAN: slab-use-after-free in fib_table_lookup (net/ipv4/fib_trie.c:1601)\n Read of size 1 at addr ffff88810676d4eb by task exploit/297\n Call Trace:\n  fib_table_lookup (net/ipv4/fib_trie.c:1601)\n  ip_route_output_key_hash_rcu (net/ipv4/route.c:2814)\n  ip_route_output_key_hash (net/ipv4/route.c:2705)\n  __ip4_datagram_connect (net/ipv4/datagram.c:49)\n  udp_connect (net/ipv4/udp.c:2144)\n  __sys_connect (net/socket.c:2167)\n  __x64_sys_connect (net/socket.c:2173)\n  do_syscall_64\n  entry_SYSCALL_64_after_hwframe\n which belongs to the cache ip_fib_alias of size 56\n\nTriggering the error path needs CAP_NET_ADMIN and a registered fib\nnotifier that can reject a route; a netdevsim device whose IPv4 FIB\nresource is exhausted is enough.\n\nFree new_fa with alias_free_mem_rcu(), as fib_table_delete() already\ndoes for a fib_alias removed from the trie.","cvssScore":null,"cvssSeverity":null,"cvssVector":null,"cwes":[],"vendors":[],"products":[],"references":[{"url":"https://git.kernel.org/stable/c/8150b5365f026e72250cacc527ea00be30f40105","tags":[]},{"url":"https://git.kernel.org/stable/c/b8d2ea75c76abcd0d72679c2f488271f573e32fb","tags":[]},{"url":"https://git.kernel.org/stable/c/cb8be318b4432abd88d3172ec157330f27a5f7a7","tags":[]},{"url":"https://git.kernel.org/stable/c/d007056868723de9c0cc3f5ffaad47a8d468b9a4","tags":[]},{"url":"https://git.kernel.org/stable/c/f2f152e94a67bc746afaf05a1b2702c195553112","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":null}