GHSA-Q235-77FH-M2C6
Vulnerability from github – Published: 2026-08-05 09:31 – Updated: 2026-08-05 09:31In the Linux kernel, the following vulnerability has been resolved:
ipv4: fib: free fib_alias with kfree_rcu() on insert error path
fib_table_insert() publishes new_fa into the leaf's fa_list with fib_insert_alias() before calling the fib entry notifiers. When a notifier fails, the error path removes new_fa with fib_remove_alias() (hlist_del_rcu) and frees it right away with kmem_cache_free().
fib_table_lookup() walks that list under rcu_read_lock() only, so a concurrent lookup that already reached new_fa keeps reading it after the free:
BUG: KASAN: slab-use-after-free in fib_table_lookup (net/ipv4/fib_trie.c:1601) Read of size 1 at addr ffff88810676d4eb by task exploit/297 Call Trace: fib_table_lookup (net/ipv4/fib_trie.c:1601) ip_route_output_key_hash_rcu (net/ipv4/route.c:2814) ip_route_output_key_hash (net/ipv4/route.c:2705) __ip4_datagram_connect (net/ipv4/datagram.c:49) udp_connect (net/ipv4/udp.c:2144) __sys_connect (net/socket.c:2167) __x64_sys_connect (net/socket.c:2173) do_syscall_64 entry_SYSCALL_64_after_hwframe which belongs to the cache ip_fib_alias of size 56
Triggering the error path needs CAP_NET_ADMIN and a registered fib notifier that can reject a route; a netdevsim device whose IPv4 FIB resource is exhausted is enough.
Free new_fa with alias_free_mem_rcu(), as fib_table_delete() already does for a fib_alias removed from the trie.
{
"affected": [],
"aliases": [
"CVE-2026-64572"
],
"database_specific": {
"cwe_ids": [],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-08-05T08:16:36Z",
"severity": null
},
"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\u0027s 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.",
"id": "GHSA-q235-77fh-m2c6",
"modified": "2026-08-05T09:31:17Z",
"published": "2026-08-05T09:31:17Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-64572"
},
{
"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"
}
],
"schema_version": "1.4.0",
"severity": []
}
Sightings
| Author | Source | Type | Date | Other |
|---|
Nomenclature
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