CVE-2026-23381: Linux kernel · net: bridge: fix nd_tbl NULL dereference when IPv6 is disabled
Affects Linux kernelSource GCVE Database
Not known to be exploited · CVSS 5.5 Medium · fixed in 5.15.0-1112.119~20.04.1 : update Linux kernel when convenient.
Data as of 26 Oct 2026, 17:16 UTC
- EPSS
- 0.1% chance of exploitation in 30 days – higher than 2% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
- Patch
- Available – fixed in 5.15.0-1112.119~20.04.1, 5.15.0-1117.126~20.04.1, 5.15.0-1117.126~20.04.2 +63
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:HExploitation evidence
Disclosed: evidence found.
CVE published 25 Mar 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponised: 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 26 Oct 2026.
What to do
Upgrade to a fixed release listed under Affected software.
Affected software
| Product | Affected | Fixed in |
|---|---|---|
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Ubuntu 25.10linux-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther threats | Affected
| Fixed in– |
Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.
AI-suggested
A patch is available that fixes this vulnerability by correcting the IPv6 status check in the bridge code. Users should apply the official Linux kernel updates that include this fix. The vendor advisory confirms the availability of this fix. No additional mitigation is required once patched.
Description
A vulnerability in the Linux kernel's bridge networking code causes a NULL pointer dereference when IPv6 is disabled and certain Neighbor Discovery suppression features are enabled. This occurs because the nd_tbl structure is not initialized when booting with the 'ipv6.disable=1' parameter, leading to a kernel crash upon receiving specific ICMPv6 packets. The issue has been fixed by changing the condition that checks IPv6 status, effectively disabling Neighbor Discovery suppression when IPv6 is disabled.
References
- ubuntu.com/security/CVE-2026-23381 (opens in a new tab)
- cve.org/CVERecord?id=CVE-2026-23381 (opens in a new tab)
- git.kernel.org/linus/e5e890630533bdc15b26a34bb8e7ef539bdf1322 (opens in a new tab)
- git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6 (opens in a new tab)
- git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55 (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/e5e890630533bdc15b26a34bb8e7ef539bdf1322 (opens in a new tab)
- ubuntu.com/security/notices/USN-8567-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8574-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8596-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8575-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8576-2 (opens in a new tab)
- ubuntu.com/security/notices/USN-8597-1 (opens in a new tab)
- ubuntu.com/security/notices/USN-8595-2 (opens in a new tab)