{"id":"CVE-2026-64572","summary":"ipv4: fib: free fib_alias with kfree_rcu() on insert error path","details":"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.","modified":"2026-08-07T03:45:53.045677313Z","published":"2026-08-05T08:08:09.068Z","database_specific":{"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64572.json","cna_assigner":"Linux"},"references":[{"type":"WEB","url":"https://git.kernel.org/stable/c/8150b5365f026e72250cacc527ea00be30f40105"},{"type":"WEB","url":"https://git.kernel.org/stable/c/b8d2ea75c76abcd0d72679c2f488271f573e32fb"},{"type":"WEB","url":"https://git.kernel.org/stable/c/cb8be318b4432abd88d3172ec157330f27a5f7a7"},{"type":"WEB","url":"https://git.kernel.org/stable/c/d007056868723de9c0cc3f5ffaad47a8d468b9a4"},{"type":"WEB","url":"https://git.kernel.org/stable/c/f2f152e94a67bc746afaf05a1b2702c195553112"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64572.json"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-64572"},{"type":"PACKAGE","url":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git","events":[{"introduced":"a6c76c17df021b141b0d306828c9fe4ba2d2717c"},{"fixed":"8150b5365f026e72250cacc527ea00be30f40105"},{"fixed":"d007056868723de9c0cc3f5ffaad47a8d468b9a4"},{"fixed":"cb8be318b4432abd88d3172ec157330f27a5f7a7"},{"fixed":"b8d2ea75c76abcd0d72679c2f488271f573e32fb"},{"fixed":"f2f152e94a67bc746afaf05a1b2702c195553112"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64572.json"}},{"package":{"name":"Kernel","ecosystem":"Linux"},"ranges":[{"type":"ECOSYSTEM","events":[{"introduced":"5.6.0"},{"fixed":"6.6.148"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.7.0"},{"fixed":"6.12.101"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.13.0"},{"fixed":"6.18.42"}]},{"type":"ECOSYSTEM","events":[{"introduced":"6.19.0"},{"fixed":"7.1.6"}]}],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-64572.json"}}],"schema_version":"1.8.0"}