CVE-2026-64572 (GCVE-0-2026-64572)
Vulnerability from cvelistv5
Published
2026-08-05 08:08
Modified
2026-08-19 16:28
Severity ?
VLAI Severity ?
EPSS score ?
Summary
In 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.
References
Impacted products
| Vendor | Product | Version | ||
|---|---|---|---|---|
| Linux | Linux |
Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c Version: a6c76c17df021b141b0d306828c9fe4ba2d2717c |
||
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"descriptions": [
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"value": "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."
}
],
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"dateUpdated": "2026-08-19T16:28:49.541Z",
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"title": "ipv4: fib: free fib_alias with kfree_rcu() on insert error path",
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"cveId": "CVE-2026-64572",
"datePublished": "2026-08-05T08:08:09.068Z",
"dateReserved": "2026-07-19T15:36:31.797Z",
"dateUpdated": "2026-08-19T16:28:49.541Z",
"state": "PUBLISHED"
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"dataType": "CVE_RECORD",
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}
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Sightings
| Author | Source | Type | Date |
|---|
Nomenclature
- Seen: The vulnerability was mentioned, discussed, or seen somewhere by the user.
- Confirmed: The vulnerability is confirmed from an analyst perspective.
- Published Proof of Concept: A public proof of concept is available for this vulnerability.
- Exploited: This vulnerability was exploited and seen by the user reporting the sighting.
- Patched: This vulnerability was successfully patched by the user reporting the sighting.
- Not exploited: This vulnerability was not exploited or seen by the user reporting the sighting.
- Not confirmed: The user expresses doubt about the veracity of the vulnerability.
- Not patched: This vulnerability was not successfully patched by the user reporting the sighting.
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