{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-64123",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-64123"
  ],
  "published": "2026-07-19T15:41:06Z",
  "summary": "net: hsr: defer node table free until after RCU readers",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: hsr: defer node table free until after RCU readers\n\nHSR node-list and node-status generic-netlink operations run under\nrcu_read_lock(). They walk hsr->node_db through hsr_get_next_node() and\nhsr_get_node_data(), but RTM_DELLINK teardown removes the same node table\nwith plain list_del() and frees each node immediately.\n\nThat lets a generic-netlink reader hold a struct hsr_node pointer across\nhsr_dellink(). In a KASAN build, widening the reader window after\nhsr_get_next_node() obtains the node reproduces a slab-use-after-free\nwhen the reader copies node->macaddress_A; the freeing stack is\nhsr_del_nodes() from hsr_dellink().\n\nUse list_del_rcu() and defer the free through the existing\nhsr_free_node_rcu() callback. This matches the lifetime rule used by the\nHSR prune paths, which already delete nodes with list_del_rcu() and\ncall_rcu().",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H"
    }
  ],
  "affected": [
    {
      "package": {
        "ecosystem": "Raspberry Pi OS:12",
        "name": "linux"
      },
      "versions": [
        "1:6.1.47-1+rpt4"
      ],
      "ecosystem_specific": {
        "binaries": [
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-2712",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v6",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v7l",
            "binary_version": "1:6.1.47-1+rpt4"
          },
          {
            "binary_name": "linux-image-6.1.0-rpi3-rpi-v8",
            "binary_version": "1:6.1.47-1+rpt4"
          }
        ]
      },
      "database_specific": {
        "per_version": {
          "1:6.1.47-1+rpt4": {
            "linux_commit": "655fc658a15ae7a6f37103754adb39ba52a9a14e",
            "upstream_version": "6.1.47",
            "assessment": "commit ancestry (strak rule)",
            "upstream_fixed": "6.1.176",
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-64123"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/0ea70fb46940620848c08d9d399455c9e82fecdb"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8be6685cdd1255bcc85f9b59e4bfc313aefc5c1b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/c5580114e0492bcd2e0a37613ed4c311e3fa3d4d"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7713f4aafb577ff49fa67f0488d9c7dddc64d6ce"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6324423a8e6591f41a16c09a8f9a84e554ac147c"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/8c3af18bb0d7c921a5219194037509463eb2ffde"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/aaec7096f9961eb223b5b149abe9495525c205d9"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T13:16:28Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - Exploitation requires local netlink access: generic-netlink HSR_C_GET_NODE_LIST/HSR_C_GET_NODE_STATUS and rtnetlink RTM_DELLINK. The bug is not reachable via HSR/PRP network frames despite HSR being a network redundancy protocol.\nAC:L - The attacker controls both sides of the race by issuing concurrent GENL node queries and RTM_DELLINK on separate threads; no unpredictable victim state or memory layout is required beyond having an HSR interface configured.\nPR:L - Reliable exploitation requires CAP_NET_ADMIN to delete the HSR device via RTM_DELLINK (and typically to create it); CAP_NET_ADMIN is obtainable by an unprivileged user through user namespaces (unshare -Urn), and the GENL read operations themselves carry no admin-perm flag.\nUI:N - No victim interaction is required; the race is triggered entirely by the attacker's own concurrent netlink operations.\nS:U - Impact is confined to kernel memory corruption and privilege escalation within the same kernel/host security boundary, not a cross-boundary escape such as VM or sandbox breakout.\nC:H - This is a slab use-after-free on struct hsr_node; freed objects can be reallocated and read through fields like macaddress_A/B and block_buf, enabling arbitrary kernel memory disclosure.\nI:H - UAF on a kmalloc'd hsr_node with spinlock and pointer fields (block_buf, seq_blocks) provides standard heap-spray primitives for arbitrary kernel writes and potential code execution.\nA:H - Use-after-free on hsr_node during RCU-protected traversal causes kernel oops/panic even without full exploitation, as confirmed by KASAN on the macaddress_A copy path."
    }
  }
}