{"id":"CVE-2026-64572","title":"ipv4: fib: free fib_alias with kfree_rcu() on insert error path","summary":"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 …","severity":"none","vendor":"Linux","product":"Linux","affected":["Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < 9d0778571def598c31e84a38ae5a7ebc6f65e6d8","Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < bb03350f974aec352b660d032a1d283eb462165a","Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < 6429c9cfd941e62acd7bb0bc64d631574d4c3b2a","Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < 8150b5365f026e72250cacc527ea00be30f40105","Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < d007056868723de9c0cc3f5ffaad47a8d468b9a4","Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < cb8be318b4432abd88d3172ec157330f27a5f7a7","Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < b8d2ea75c76abcd0d72679c2f488271f573e32fb","Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < f2f152e94a67bc746afaf05a1b2702c195553112","Linux 5.6"],"ssvc":{"exploitation":"none","automatable":"no","technicalImpact":"partial","timestamp":"2026-11-06T16:41:42.353630Z"},"published":"2026-08-05","updated":"2026-11-06","sourceUpdated":"2026-11-06T16:44:57.697Z","source":"CVEORG","sourceUrl":"https://www.cve.org/CVERecord?id=CVE-2026-64572","references":[{"url":"https://git.kernel.org/stable/c/9d0778571def598c31e84a38ae5a7ebc6f65e6d8"},{"url":"https://git.kernel.org/stable/c/bb03350f974aec352b660d032a1d283eb462165a"},{"url":"https://git.kernel.org/stable/c/6429c9cfd941e62acd7bb0bc64d631574d4c3b2a"},{"url":"https://git.kernel.org/stable/c/8150b5365f026e72250cacc527ea00be30f40105"},{"url":"https://git.kernel.org/stable/c/d007056868723de9c0cc3f5ffaad47a8d468b9a4"},{"url":"https://git.kernel.org/stable/c/cb8be318b4432abd88d3172ec157330f27a5f7a7"},{"url":"https://git.kernel.org/stable/c/b8d2ea75c76abcd0d72679c2f488271f573e32fb"},{"url":"https://git.kernel.org/stable/c/f2f152e94a67bc746afaf05a1b2702c195553112"}],"tags":["cve.org"],"epss":0.00201,"epssPercentile":0.10123,"ingestedAt":"2026-11-06T16:57:43.150Z","slug":"CVE-2026-64572","body":"## Overview\n\nIn 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.\n\n## Affected\n\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < 9d0778571def598c31e84a38ae5a7ebc6f65e6d8`\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < bb03350f974aec352b660d032a1d283eb462165a`\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < 6429c9cfd941e62acd7bb0bc64d631574d4c3b2a`\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < 8150b5365f026e72250cacc527ea00be30f40105`\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < d007056868723de9c0cc3f5ffaad47a8d468b9a4`\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < cb8be318b4432abd88d3172ec157330f27a5f7a7`\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < b8d2ea75c76abcd0d72679c2f488271f573e32fb`\n- `Linux >= a6c76c17df021b141b0d306828c9fe4ba2d2717c < f2f152e94a67bc746afaf05a1b2702c195553112`\n- `Linux 5.6`\n\n## Remediation\n\nRefer to the linked advisories for vendor-supplied fixes and affected version ranges.","depth":"sunlit","depthScore":3,"depthScoreParts":{"impact":2.8,"likelihood":0,"exploitation":0,"ransomware":0},"changes":[]}