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VulnerabilityPublished Updated

CVE-2026-23200: Linux kernel · ipv6: Fix ECMP sibling count mismatch when clearing RTF_ADDRCONF

Affects Linux kernelSource GCVE Database

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Not known to be exploited · CVSS 5.5 Medium · fixed in 6.8.0-1057.60~22.04.1 : update Linux kernel when convenient.

Data as of 5 Nov 2026, 00:01 UTC

CVSS 3.1 base score
5.5Medium
How severe the flaw is on the 0–10 CVSS scale.
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 6.8.0-1057.60~22.04.1, 6.8.0-1060.63~22.04.1, 6.8.0-124.124~22.04.1 +27
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 14 Feb 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq 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 4 Nov 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 25.10linuxpkg:deb/ubuntu/linux?arch=source&distro=questingOther threatsAffected
  • 6.14.0-15.15 – 6.17.0-40.40
20 affected builds
Fixed in–
Ubuntu 25.10linux-gcppkg:deb/ubuntu/linux-gcp?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1006.6 – 6.17.0-1020.22
17 affected builds
Fixed in–
Ubuntu 25.10linux-raspipkg:deb/ubuntu/linux-raspi?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1005.5 – 6.17.0-1021.21
14 affected builds
Fixed in–
Ubuntu 25.10linux-riscvpkg:deb/ubuntu/linux-riscv?arch=source&distro=questingOther threatsAffected
  • 6.14.0-13.13.2 – 6.17.0-40.40.1
15 affected builds
Fixed in–
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-117.117
Fixed in
  • 6.8.0-117.117
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1055.58
Fixed in
  • 6.8.0-1055.58

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 and has been released in Linux kernel versions 6.8.0-1054.55 and later (including various 6.8.0 and 6.8.1 builds for Ubuntu 22.04 LTS). Users should update to these fixed kernel versions to remediate the issue. No additional mitigation actions are required beyond applying the official kernel updates.

Description

A vulnerability in the Linux kernel IPv6 implementation caused a kernel BUG due to a mismatch in ECMP sibling counts when clearing the RTF_ADDRCONF flag on routes with gateways. This flaw was introduced by a commit that cleared RTF_ADDRCONF from existing routes when adding static routes with the same nexthop, but did not account for routes with gateways becoming ECMP-eligible without being added to the fib6_siblings list. This mismatch leads to a kernel crash in fib6_add_rt2node(). The issue is fixed by only clearing RTF_ADDRCONF on routes without gateways.

References

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