Medium 5.5Published Mar 25, 2026

CVE-2026-23381net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled

Updated under an hour ago (Oct 26, 2026, 10:40 PM ET)

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Exploited in the last 30 days

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: <IRQ> ? 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.

CVSS: 5.5 MEDIUM (v3.1, NVD)CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Weakness (CWE): Not given
Known exploited: Not in CISA's KEV catalog
EPSS (exploitation in the next 30 days): Not loaded for this CVE
Assigned by: Linux
NVD analysis: Modified
Record last updated: Oct 14, 2026
First seen by InfoSec Signals: Oct 9, 2026

Affected products

Affected products

Linux Linux linux:linux (from the name)	from ed842faeb2bd49256f00485402f3113205f91d30 before a9d712ccfeef737c0e700a4b5b98f310e07b6b60; from ed842faeb2bd49256f00485402f3113205f91d30 before a5c56e65b685360dd3f2278aeff8c21061feb665; from ed842faeb2bd49256f00485402f3113205f91d30 before 7a894eb5de246d79f13105c55a67381039a24d44; from ed842faeb2bd49256f00485402f3113205f91d30 before a12cdaa3375f0bd3c8f4e564be7c143529abfe5b; from ed842faeb2bd49256f00485402f3113205f91d30 before aa73deb3b6b730ec280d45b3f423bfa9e17bc122; from ed842faeb2bd49256f00485402f3113205f91d30 before 33dec6f10777d5a8f71c0a200f690da5ae3c2e55; from ed842faeb2bd49256f00485402f3113205f91d30 before 20ef5c25422f97dd09d751e5ae6c18406cdc78e6; from ed842faeb2bd49256f00485402f3113205f91d30 before e5e890630533bdc15b26a34bb8e7ef539bdf1322	CNA record
Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP siemens:simatic_s7_1500_cpu_1518f_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
Siemens SIMATIC S7-1500 TM MFP - GNU/Linux subsystem siemens:simatic_s7_1500_tm_mfp_gnu_linux_subsystem (from the name)	all versions	CISA ADP
Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP siemens:siplus_s7_1500_cpu_1518_4_pn_dp_mfp (from the name)	from V3.1.6	CISA ADP
linux linux_kernel linux:linux_kernel	from 4.15.1 before 5.10.253; from 5.11 before 5.15.203; from 5.16 before 6.1.167; from 6.2 before 6.6.130; from 6.7 before 6.12.77; from 6.13 before 6.18.17; from 6.19 before 6.19.7; 4.15; and 7 more ranges	NVD

References

References

https://git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60	patch
https://git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665	patch
https://git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44	patch
https://git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b	patch
https://git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122	patch
https://git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55	patch
https://git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6	patch
https://git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322	patch
https://cert-portal.siemens.com/productcert/html/ssa-019113.html
https://cert-portal.siemens.com/productcert/html/ssa-082556.html
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The CVE record on cve.org NVD's entry

The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.