{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2024-35839",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2024-35839"
  ],
  "published": "2024-05-17T14:32:10Z",
  "summary": "netfilter: bridge: replace physindev with physinif in nf_bridge_info",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnetfilter: bridge: replace physindev with physinif in nf_bridge_info\n\nAn skb can be added to a neigh->arp_queue while waiting for an arp\nreply. Where original skb's skb->dev can be different to neigh's\nneigh->dev. For instance in case of bridging dnated skb from one veth to\nanother, the skb would be added to a neigh->arp_queue of the bridge.\n\nAs skb->dev can be reset back to nf_bridge->physindev and used, and as\nthere is no explicit mechanism that prevents this physindev from been\nfreed under us (for instance neigh_flush_dev doesn't cleanup skbs from\ndifferent device's neigh queue) we can crash on e.g. this stack:\n\narp_process\n  neigh_update\n    skb = __skb_dequeue(&neigh->arp_queue)\n      neigh_resolve_output(..., skb)\n        ...\n          br_nf_dev_xmit\n            br_nf_pre_routing_finish_bridge_slow\n              skb->dev = nf_bridge->physindev\n              br_handle_frame_finish\n\nLet's use plain ifindex instead of net_device link. To peek into the\noriginal net_device we will use dev_get_by_index_rcu(). Thus either we\nget device and are safe to use it or we don't get it and drop skb.",
  "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"
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        "1:6.1.58-1+rpt2",
        "1:6.1.63-1+rpt1",
        "1:6.1.73-1+rpt1"
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      "ecosystem_specific": {
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  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2024-35839"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/7ae19ee81ca56b13c50a78de6c47d5b8fdc9d97b"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/9325e3188a9cf3f69fc6f32af59844bbc5b90547"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/544add1f1cfb78c3dfa3e6edcf4668f6be5e730c"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/9874808878d9eed407e3977fd11fee49de1e1d86"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-05T11:52:36Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 7.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - The full trigger chain requires local control of netdev lifecycle (creating a bridge/veth topology, installing a DNAT rule, and deleting the ingress port) in addition to injecting the packet, all done through netlink/sysctl in the attacker's own network namespace. Consistent with netfilter/bridge configuration paths being locally reachable.\nAC:L - The attacker deterministically controls every step and their ordering \u2014 DNAT to an address with no neighbour entry, veth deletion, then the ARP reply that dequeues the skb \u2014 and can stretch the arp_queue residency window arbitrarily via the per-netns neigh sysctls (retrans_time_ms/mcast_solicit), giving ample time to reclaim the freed net_device.\nPR:L - An unprivileged user gets CAP_NET_ADMIN in a new netns via `unshare -Urn`, and br_netfilter_sysctl_default() enables bridge-nf-call-iptables/ip6tables by default in every new netns, so no real privilege is needed to arm and reach the path.\nUI:N - The attacker performs the entire sequence \u2014 topology setup, packet injection, device teardown, ARP reply \u2014 with no victim action required.\nS:U - The use-after-free corrupts kernel memory within the same security authority; there is no VM, IOMMU, or hypervisor boundary crossed.\nC:H - Use-after-free on a struct net_device whose fields are re-read after free (dev->nd_net, dev->rx_handler_data), giving a reclaim-controlled pointer that is dereferenced \u2014 an arbitrary kernel read primitive once the allocation is sprayed.\nI:H - The freed device's rx_handler_data is type-confused into a struct net_bridge_port and written through (br_fdb_update), and the attacker-controlled struct net * from dev_net() feeds NF_HOOK's function-pointer dispatch, enabling arbitrary write and control-flow hijack.\nA:H - Dereferencing the freed net_device reliably oopses/panics the kernel, as observed in the reported production crash stack, and can be triggered repeatedly."
    }
  }
}