{
  "schema_version": "1.6.1",
  "id": "RPI-CVE-2026-72423",
  "modified": "2026-10-09T11:39:44Z",
  "upstream": [
    "CVE-2026-72423"
  ],
  "published": "2026-08-15T06:04:33Z",
  "summary": "bpf: Guard conntrack opts error writes",
  "details": "In the Linux kernel, the following vulnerability has been resolved:\n\nbpf: Guard conntrack opts error writes\n\nThe conntrack lookup and allocation kfuncs take an opts pointer\ntogether with an opts__sz argument. The verifier checks only the memory\nrange described by opts__sz, but the wrappers unconditionally write\nopts->error whenever the internal lookup or allocation helper returns an\nerror.\n\nFor an invalid size smaller than the end of opts->error, that write can\nland outside the verifier-checked range. Keep returning NULL for invalid\narguments, but only report the error through opts->error when the\nsupplied size includes the field.\n\nThis preserves error reporting for the supported 12-byte and 16-byte\nlayouts, and for other invalid sizes that still include opts->error.",
  "severity": [
    {
      "type": "CVSS_V3",
      "score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/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": null,
            "compiled_filter": false
          }
        }
      }
    }
  ],
  "references": [
    {
      "type": "ADVISORY",
      "url": "https://www.cve.org/CVERecord?id=CVE-2026-72423"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/dd74c80203842a21b2ebb9f70d1260d9aa20fa05"
    },
    {
      "type": "FIX",
      "url": "https://git.kernel.org/stable/c/6f6183a39533d727deaa5061cadae6dd9e6744d0"
    }
  ],
  "database_specific": {
    "source": "https://git.kernel.org/pub/scm/linux/security/vulns.git",
    "upstream_modified": "2026-08-17T05:50:24Z",
    "severity": {
      "source": "kernel CNA",
      "cvss_v3_score": 8.8,
      "cvss_v3_severity": "High",
      "scenario": "AV:L - Exploitation requires loading and attaching a BPF XDP or TC program that calls the conntrack kfuncs via the bpf() syscall; per kernel CNA guidance BPF/netfilter paths are Local even when programs later run on network packets.\nAC:L - An attacker reliably triggers the bug by calling bpf_xdp_ct_lookup/alloc or bpf_skb_ct_lookup/alloc with opts__sz smaller than the error field (e.g. 4); the helper returns EINVAL and the wrapper performs the out-of-bounds write with no races or attacker-uncontrollable conditions.\nPR:L - Loading BPF_PROG_TYPE_XDP or BPF_PROG_TYPE_SCHED_CLS programs requires CAP_NET_ADMIN, which unprivileged users can obtain inside user/network namespaces (unshare -Urn) on typical Linux deployments without init-namespace root.\nUI:N - No victim interaction is required; the attacker loads their own BPF program and invokes the kfunc with a small opts__sz to trigger the out-of-bounds write on demand.\nS:C - Corrupting kernel memory via a verifier-bypassing BPF stack write from a user/network namespace can cross the namespace/container trust boundary to compromise the host kernel, exceeding the attacker's original security scope.\nC:H - The bug is a controlled 4-byte out-of-bounds write past the verifier-approved opts buffer on the BPF stack, a memory-corruption primitive that can be leveraged for arbitrary kernel memory disclosure.\nI:H - Writing opts->error outside the verifier-checked range corrupts adjacent BPF stack slots with attacker-influenced errno values, enabling heap/stack grooming and control-flow hijacking toward arbitrary kernel code execution.\nA:H - Corrupting BPF stack memory outside verifier bounds can cause immediate kernel oops/panic or be used in a repeatable crash/DoS loop when the attached XDP/TC program runs on incoming traffic."
    }
  }
}