CVE-2026-64423 (GCVE-0-2026-64423)
Vulnerability from cvelistv5
Published
2026-07-25 08:51
Modified
2026-08-17 04:55
Severity ?
7.8 (High) - CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
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: <IRQ> 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 </IRQ> 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+0x16fa/0x2010 ip_setsockopt+0x3f/0x90 do_sock_setsockopt+0x1ad/0x300 Freed by task 0: kasan_save_track+0x3e/0x80 kasan_save_free_info+0x40/0x50 __kasan_slab_free+0x3a/0x60 __rcu_free_sheaf_prepare+0xd4/0x220 rcu_free_sheaf+0x36/0x190 rcu_core+0x8d9/0x12f0 handle_softirqs+0x236/0x7f0
References
Impacted products
Vendor Product Version
Linux Linux Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
Version: e9897071350bd9d94a56b5b6f79c85b1a98fc7e7
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{
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          "defaultStatus": "unaffected",
          "product": "Linux",
          "programFiles": [
            "net/ipv4/igmp.c"
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          "vendor": "Linux",
          "versions": [
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              "status": "unaffected",
              "version": "5.10.261",
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              "status": "unaffected",
              "version": "5.15.212",
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            },
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              "status": "unaffected",
              "version": "6.1.178",
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              "version": "6.12.96",
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              "lessThanOrEqual": "*",
              "status": "unaffected",
              "version": "7.2",
              "versionType": "original_commit_for_fix"
            }
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        }
      ],
      "cpeApplicability": [
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              "negate": false,
              "operator": "OR"
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          ]
        }
      ],
      "descriptions": [
        {
          "lang": "en",
          "value": "In the Linux kernel, the following vulnerability has been resolved:\n\nipv4: igmp: remove multicast group from hash table on device destruction\n\nWhen a device is destroyed under RTNL, ip_mc_destroy_dev() iterates through\nthe multicast list and calls ip_ma_put() on each membership, scheduling\nthem for RCU reclamation. However, they are not unlinked from the device\u0027s\nmulticast hash table (mc_hash).\n\nSince the device remains published in dev-\u003eip_ptr until after\nip_mc_destroy_dev() completes, concurrent RCU readers traversing mc_hash\ncan still locate and access the multicast group after its refcount is\ndecremented. If the RCU callback runs and frees the group while a reader is\naccessing it, a use-after-free occurs.\n\nFix this by unlinking the multicast group from mc_hash using\nip_mc_hash_remove() before scheduling it for reclamation.\n\nBUG: KASAN: slab-use-after-free in ip_check_mc_rcu+0x149/0x3f0\nRead of size 4 at addr ffff888009bf1408 by task mausezahn/2276\n\nCall Trace:\n \u003cIRQ\u003e\n dump_stack_lvl+0x67/0x90\n print_report+0x175/0x7c0\n kasan_report+0x147/0x180\n ip_check_mc_rcu+0x149/0x3f0\n udp_v4_early_demux+0x36d/0x12d0\n ip_rcv_finish_core+0xb8b/0x1390\n ip_rcv_finish+0x54/0x120\n NF_HOOK+0x213/0x2b0\n __netif_receive_skb+0x126/0x340\n process_backlog+0x4f2/0xf00\n __napi_poll+0x92/0x2c0\n net_rx_action+0x583/0xc60\n handle_softirqs+0x236/0x7f0\n do_softirq+0x57/0x80\n \u003c/IRQ\u003e\n\nAllocated by task 2239:\n kasan_save_track+0x3e/0x80\n __kasan_kmalloc+0x72/0x90\n ____ip_mc_inc_group+0x31a/0xa40\n __ip_mc_join_group+0x334/0x3f0\n do_ip_setsockopt+0x16fa/0x2010\n ip_setsockopt+0x3f/0x90\n do_sock_setsockopt+0x1ad/0x300\n\nFreed by task 0:\n kasan_save_track+0x3e/0x80\n kasan_save_free_info+0x40/0x50\n __kasan_slab_free+0x3a/0x60\n __rcu_free_sheaf_prepare+0xd4/0x220\n rcu_free_sheaf+0x36/0x190\n rcu_core+0x8d9/0x12f0\n handle_softirqs+0x236/0x7f0"
        }
      ],
      "metrics": [
        {
          "cvssV3_1": {
            "baseScore": 7.8,
            "baseSeverity": "HIGH",
            "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H",
            "version": "3.1"
          },
          "scenarios": [
            {
              "lang": "en",
              "value": "AV:L - An end-to-end attacker-controlled trigger requires local socket and netlink operations to create multicast memberships and concurrently destroy IPv4 device state; received multicast packets alone cannot initiate the necessary teardown. These operations are reachable inside an attacker-created user and network namespace.\nAC:L - The attacker can populate mc_hash, generate continuous multicast traffic, and repeatedly tear down IPv4 state, controlling both sides of the race. No victim-dependent timing or secret state is required.\nPR:L - Device teardown or invalid-MTU configuration requires CAP_NET_ADMIN in the target network namespace, while multicast joins and UDP sends are unprivileged. An ordinary user can obtain this namespace-scoped capability through unprivileged user and network namespaces.\nUI:N - Exploitation requires no action by another user once the attacker can execute locally and create the required namespace and traffic.\nS:U - The vulnerable code and resulting host-kernel compromise remain within the same security authority; this is conventional kernel privilege escalation rather than a guest-to-host escape.\nC:H - The stale kmalloc-256 ip_mc_list entry exposes reuse-controlled fields and pointers to kernel reads, making kernel-memory disclosure and broader read primitives plausible.\nI:H - Reallocation permits attacker-influenced object contents to drive spinlock writes and pointer traversal on freed memory, making heap corruption and control-flow hijacking defensible.\nA:H - The confirmed slab use-after-free can dereference corrupted hash pointers or operate on an invalid spinlock, causing a kernel oops, panic, general-protection fault, or hang."
            }
          ]
        }
      ],
      "providerMetadata": {
        "dateUpdated": "2026-08-17T04:55:23.253Z",
        "orgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
        "shortName": "Linux"
      },
      "references": [
        {
          "url": "https://git.kernel.org/stable/c/412ba7def06ffe974ba9a1d862b022362c54ffa5"
        },
        {
          "url": "https://git.kernel.org/stable/c/c6cb5f8ebe1c1a78710c19f102db9fe48b9e6ba9"
        },
        {
          "url": "https://git.kernel.org/stable/c/5f42729d74bd6c61306d864423290d92962de4e1"
        },
        {
          "url": "https://git.kernel.org/stable/c/76d030ac95e17f91d69a595f17ebc5979700cf9a"
        },
        {
          "url": "https://git.kernel.org/stable/c/8820b530cb2388503d7418228d03ba074bf7a03e"
        },
        {
          "url": "https://git.kernel.org/stable/c/2ca18df1c2611f70eb3eb487e02ae85eb703b284"
        },
        {
          "url": "https://git.kernel.org/stable/c/f91883031e5a62877a29ce139442973cbea769f1"
        },
        {
          "url": "https://git.kernel.org/stable/c/7993211bde166471dffac074dc965489f86531f8"
        }
      ],
      "title": "ipv4: igmp: remove multicast group from hash table on device destruction",
      "x_generator": {
        "engine": "bippy-1.2.0"
      }
    }
  },
  "cveMetadata": {
    "assignerOrgId": "416baaa9-dc9f-4396-8d5f-8c081fb06d67",
    "assignerShortName": "Linux",
    "cveId": "CVE-2026-64423",
    "datePublished": "2026-07-25T08:51:01.485Z",
    "dateReserved": "2026-07-19T15:36:31.787Z",
    "dateUpdated": "2026-08-17T04:55:23.253Z",
    "state": "PUBLISHED"
  },
  "dataType": "CVE_RECORD",
  "dataVersion": "5.2"
}


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