CVE-2026-23381: Linux kernel · net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled
Affects Linux kernelSource CVE Database V5
Not known to be exploited · fixed in e5e890630533bdc15b26a34bb8e7ef539bdf1322 : update Linux kernel when convenient.
Data as of 5 Nov 2026, 22:04 UTC
Rated by Threat Radar · No CVSS score from NVD or the CNA
Thin evidence
One scorer or none- CISA SSVC
- Exploitation
- No evidence of active exploitation and no public proof of concept
- Automatable
- Attackers cannot reliably automate steps 1–4 of the kill chain
- Technical impact
- Limited control over the software or limited information exposure
CISA SSVC assessment, 2026-11-05.
- Patch
- Available – fixed in e5e890630533bdc15b26a34bb8e7ef539bdf1322, aa73deb3b6b730ec280d45b3f423bfa9e17bc122, a12cdaa3375f0bd3c8f4e564be7c143529abfe5b +5
Exploitation evidence
Disclosed: evidence found.
CVE published 25 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors
A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 5 Nov 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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| LinuxLinux | Affected
| Fixed in
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Description
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.
References
- git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60 (opens in a new tab)
- git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665 (opens in a new tab)
- git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44 (opens in a new tab)
- git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b (opens in a new tab)
- git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122 (opens in a new tab)
- git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55 (opens in a new tab)
- git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6 (opens in a new tab)
- git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322 (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-082556.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-019113.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-457936.html (opens in a new tab)
- cert-portal.siemens.com/productcert/html/ssa-784472.html (opens in a new tab)