net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled

{
  "id": "20b4787d204b98e0d5a9da3c670ea1cd7f121603ff46433101ca66ca8e8a0256",
  "url": "https://osv.dev/vulnerability/CVE-2026-23381",
  "method": "structured",
  "payload": {
    "kind": "advisory",
    "title": "net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled",
    "summary": "In the Linux kernel, the following vulnerability has been resolved: net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled When booting with the 'ipv6.disable=1' parameter, the nd_tbl is never initialized because inet6_init() exits before ndisc_init() is called which initializes it. Then, if neigh_suppress is enabled and an ICMPv6 Neighbor Discovery packet reaches the bridge, br_do_suppress_nd() will dereference ipv6_stub->nd_tbl which is NULL, passing it to neigh_lookup(). This causes a kernel NULL pointer dereference. BUG: kernel NULL pointer dereference, address: 0000000000000268 Oops: 0000 [#1] PREEMPT SMP NOPTI [...] RIP: 0010:neigh_lookup+0x16/0xe0 [...] Call Trace: ? neigh_lookup+0x16/0xe0 br_do_suppress_nd+0x160/0x290 [bridge] br_handle_frame_finish+0x500/0x620 [bridge] br_handle_frame+0x353/0x440 [bridge] __netif_receive_skb_core.constprop.0+0x298/0x1110 __netif_receive_skb_one_core+0x3d/0xa0 process_backlog+0xa0/0x140 __napi_poll+0x2c/0x170 net_rx_action+0x2c4/0x3a0 handle_softirqs+0xd0/0x270 do_softirq+0x3f/0x60 Fix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in the callers. This is in essence disabling NS/NA suppression when IPv6 is disabled.",
    "evidence": "osv:CVE-2026-23381",
    "products": [
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        "name": {
          "value": "Kernel",
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        "prerequisites": [],
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    "severity": "unknown",
    "structured": {
      "id": "CVE-2026-23381",
      "aliases": [
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      "modified": "2026-10-28T02:30:45.973283245Z",
      "provider": "osv",
      "references": [
        "https://cert-portal.siemens.com/productcert/html/ssa-019113.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-082556.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-457936.html",
        "https://cert-portal.siemens.com/productcert/html/ssa-784472.html",
        "https://git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6",
        "https://git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55",
        "https://git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44",
        "https://git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b",
        "https://git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665",
        "https://git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60",
        "https://git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122",
        "https://git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322",
        "https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/23xxx/CVE-2026-23381.json",
        "https://nvd.nist.gov/vuln/detail/CVE-2026-23381",
        "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/2026/23xxx/CVE-2026-23381.json"
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      {
        "value": "CVE-2026-23381",
        "evidence": "/id"
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    "security_relevant": true,
    "severity_evidence": null
  },
  "source_id": "core-osv",
  "document_id": 514038,
  "published_at": "2026-03-25T10:28:00.416+00:00"
}