CVE-2026-64572 (GCVE-0-2026-64572)

Vulnerability from cvelistv5 – Published: 2026-08-05 08:08 – Updated: 2026-08-05 08:08
VLAI
Title
ipv4: fib: free fib_alias with kfree_rcu() on insert error path
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.
Severity
No CVSS data available.
Assigner
References
Impacted products
Vendor Product Version
Linux Linux Affected: a6c76c17df021b141b0d306828c9fe4ba2d2717c , < 8150b5365f026e72250cacc527ea00be30f40105 (git)
Affected: a6c76c17df021b141b0d306828c9fe4ba2d2717c , < d007056868723de9c0cc3f5ffaad47a8d468b9a4 (git)
Affected: a6c76c17df021b141b0d306828c9fe4ba2d2717c , < cb8be318b4432abd88d3172ec157330f27a5f7a7 (git)
Affected: a6c76c17df021b141b0d306828c9fe4ba2d2717c , < b8d2ea75c76abcd0d72679c2f488271f573e32fb (git)
Affected: a6c76c17df021b141b0d306828c9fe4ba2d2717c , < f2f152e94a67bc746afaf05a1b2702c195553112 (git)
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Linux Linux Affected: 5.6
Unaffected: 0 , < 5.6 (semver)
Unaffected: 6.6.148 , ≤ 6.6.* (semver)
Unaffected: 6.12.101 , ≤ 6.12.* (semver)
Unaffected: 6.18.42 , ≤ 6.18.* (semver)
Unaffected: 7.1.6 , ≤ 7.1.* (semver)
Unaffected: 7.2-rc4 , ≤ * (original_commit_for_fix)
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{
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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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      "providerMetadata": {
        "dateUpdated": "2026-08-05T08:08:09.068Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
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    "dateReserved": "2026-07-19T15:36:31.797Z",
    "dateUpdated": "2026-08-05T08:08:09.068Z",
    "state": "PUBLISHED"
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    "redhat_vex": {
      "aggregate_severity": "Moderate",
      "current_release_date": "2026-08-06T10:49:09+00:00",
      "cve": "CVE-2026-64572",
      "id": "CVE-2026-64572",
      "initial_release_date": "2026-08-05T00:00:00+00:00",
      "product_status:known_affected": "232",
      "product_status:known_not_affected": "42",
      "source": "Red Hat CSAF VEX",
      "status": "final",
      "title": "kernel: ipv4: fib: free fib_alias with kfree_rcu() on insert error path",
      "url": "https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-64572.json",
      "version": "3"
    },
    "suse_vex": {
      "aggregate_severity": "moderate",
      "current_release_date": "2026-08-06T01:06:25Z",
      "cve": "CVE-2026-64572",
      "id": "CVE-2026-64572",
      "initial_release_date": "2026-08-06T01:06:25Z",
      "source": "SUSE CSAF VEX",
      "status": "interim",
      "title": "SUSE CVE CVE-2026-64572",
      "url": "https://ftp.suse.com/pub/projects/security/csaf-vex/cve-2026-64572.json",
      "version": "2"
    }
  }
}



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Forecast uses a logistic model when the trend is rising, or an exponential decay model when the trend is falling. Fitted via linearized least squares.

Sightings

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Nomenclature

  • Seen: The vulnerability was mentioned, discussed, or observed by the user.
  • Confirmed: The vulnerability has been validated from an analyst's perspective.
  • Published Proof of Concept: A public proof of concept is available for this vulnerability.
  • Exploited: The vulnerability was observed as exploited by the user who reported the sighting.
  • Patched: The vulnerability was observed as successfully patched by the user who reported the sighting.
  • Not exploited: The vulnerability was not observed as exploited by the user who reported the sighting.
  • Not confirmed: The user expressed doubt about the validity of the vulnerability.
  • Not patched: The vulnerability was not observed as successfully patched by the user who reported the sighting.


Detection rules are retrieved from Rulezet.