ipv4: igmp: remove multicast group from hash table on device destruction

{
  "id": "d5789564c068bedc20be3cf1a47ee9e534d81783f800e0c18cdc6f3462a09ad4",
  "url": "https://osv.dev/vulnerability/CVE-2026-64423",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "ipv4: igmp: remove multicast group from hash table on device destruction",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: ipv4: igmp: remove multicast group from hash table on device destruction When a device is destroyed under RTNL, ip_mc_destroy_dev() iterates through the multicast list and calls ip_ma_put() on each membership, scheduling them for RCU reclamation. However, they are not unlinked from the device's multicast hash table (mc_hash). Since the device remains published in dev->ip_ptr until after ip_mc_destroy_dev() completes, concurrent RCU readers traversing mc_hash can still locate and access the multicast group after its refcount is decremented. If the RCU callback runs and frees the group while a reader is accessing it, a use-after-free occurs. Fix this by unlinking the multicast group from mc_hash using ip_mc_hash_remove() before scheduling it for reclamation. BUG: KASAN: slab-use-after-free in ip_check_mc_rcu+0x149/0x3f0 Read of size 4 at addr ffff888009bf1408 by task mausezahn/2276 Call Trace: dump_stack_lvl+0x67/0x90 print_report+0x175/0x7c0 kasan_report+0x147/0x180 ip_check_mc_rcu+0x149/0x3f0 udp_v4_early_demux+0x36d/0x12d0 ip_rcv_finish_core+0xb8b/0x1390 ip_rcv_finish+0x54/0x120 NF_HOOK+0x213/0x2b0 __netif_receive_skb+0x126/0x340 process_backlog+0x4f2/0xf00 __napi_poll+0x92/0x2c0 net_rx_action+0x583/0xc60 handle_softirqs+0x236/0x7f0 do_softirq+0x57/0x80 Allocated by task 2239: kasan_save_track+0x3e/0x80 __kasan_kmalloc+0x72/0x90 ____ip_mc_inc_group+0x31a/0xa40 __ip_mc_join_group+0x334/0x3f0 do_ip_setsockopt+",
    "evidence": "osv:CVE-2026-64423",
    "products": [
      {
        "name": {
          "value": "Kernel",
          "evidence": "/affected/1/package/name"
        },
        "prerequisites": [],
        "fixed_versions": [
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        "affected_versions": []
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    ],
    "severity": "high",
    "structured": {
      "id": "CVE-2026-64423",
      "aliases": [
        "CVE-2026-64423"
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      "metrics": [
        {
          "type": "CVSS_V3",
          "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
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      "modified": "2026-10-28T02:30:20.686047483Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://git.kernel.org/stable/c/2ca18df1c2611f70eb3eb487e02ae85eb703b284",
        "https://git.kernel.org/stable/c/412ba7def06ffe974ba9a1d862b022362c54ffa5",
        "https://git.kernel.org/stable/c/5f42729d74bd6c61306d864423290d92962de4e1",
        "https://git.kernel.org/stable/c/76d030ac95e17f91d69a595f17ebc5979700cf9a",
        "https://git.kernel.org/stable/c/7993211bde166471dffac074dc965489f86531f8",
        "https://git.kernel.org/stable/c/8820b530cb2388503d7418228d03ba074bf7a03e",
        "https://git.kernel.org/stable/c/c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9",
        "https://git.kernel.org/stable/c/f91883031e5a62877a29ce139442973cbea769f1",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64423.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-64423",
        "https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git"
      ],
      "provider_metadata": {
        "cna_assigner": "Linux",
        "osv_generated_from": "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/64xxx/CVE-2026-64423.json"
      }
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        "value": "CVE-2026-64423",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": "/severity/0/score"
  },
  "source_id": "core-osv",
  "document_id": 487261,
  "published_at": "2026-07-25T08:51:01.485+00:00"
}