GHSA-VM87-VMVC-9C38
Vulnerability from github – Published: 2026-03-25 12:30 – Updated: 2026-07-14 15:31In 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.
{
"affected": [],
"aliases": [
"CVE-2026-23381"
],
"database_specific": {
"cwe_ids": [
"CWE-476"
],
"github_reviewed": false,
"github_reviewed_at": null,
"nvd_published_at": "2026-03-25T11:16:38Z",
"severity": "MODERATE"
},
"details": "In the Linux kernel, the following vulnerability has been resolved:\n\nnet: bridge: fix nd_tbl NULL dereference when IPv6 is disabled\n\nWhen booting with the \u0027ipv6.disable=1\u0027 parameter, the nd_tbl is never\ninitialized because inet6_init() exits before ndisc_init() is called\nwhich initializes it. Then, if neigh_suppress is enabled and an ICMPv6\nNeighbor Discovery packet reaches the bridge, br_do_suppress_nd() will\ndereference ipv6_stub-\u003end_tbl which is NULL, passing it to\nneigh_lookup(). This causes a kernel NULL pointer dereference.\n\n BUG: kernel NULL pointer dereference, address: 0000000000000268\n Oops: 0000 [#1] PREEMPT SMP NOPTI\n [...]\n RIP: 0010:neigh_lookup+0x16/0xe0\n [...]\n Call Trace:\n \u003cIRQ\u003e\n ? neigh_lookup+0x16/0xe0\n br_do_suppress_nd+0x160/0x290 [bridge]\n br_handle_frame_finish+0x500/0x620 [bridge]\n br_handle_frame+0x353/0x440 [bridge]\n __netif_receive_skb_core.constprop.0+0x298/0x1110\n __netif_receive_skb_one_core+0x3d/0xa0\n process_backlog+0xa0/0x140\n __napi_poll+0x2c/0x170\n net_rx_action+0x2c4/0x3a0\n handle_softirqs+0xd0/0x270\n do_softirq+0x3f/0x60\n\nFix this by replacing IS_ENABLED(IPV6) call with ipv6_mod_enabled() in\nthe callers. This is in essence disabling NS/NA suppression when IPv6 is\ndisabled.",
"id": "GHSA-vm87-vmvc-9c38",
"modified": "2026-07-14T15:31:43Z",
"published": "2026-03-25T12:30:24Z",
"references": [
{
"type": "ADVISORY",
"url": "https://nvd.nist.gov/vuln/detail/CVE-2026-23381"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-019113.html"
},
{
"type": "WEB",
"url": "https://cert-portal.siemens.com/productcert/html/ssa-082556.html"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122"
},
{
"type": "WEB",
"url": "https://git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322"
}
],
"schema_version": "1.4.0",
"severity": [
{
"score": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H",
"type": "CVSS_V3"
}
]
}
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