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VulnerabilityPublished Updated

CVE-2025-22021: Linux kernel · netfilter: socket: Lookup orig tuple for IPv6 SNAT

Affects Linux kernelSource GCVE Database

0

Not known to be exploited · CVSS 10.0 Critical · fixed in 5.4.0-1147.157~18.04.1 : patch Linux kernel as a priority.

Data as of 28 Oct 2026, 12:44 UTC

CVSS 3.1 base score
10.0Critical
How severe the flaw is on the 0–10 CVSS scale.
Patch
Available – fixed in 5.4.0-1147.157~18.04.1, 5.4.0-1152.159~18.04.1, 5.4.0-1150.159~18.04.1 +86
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 16 Apr 2025

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponised: 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 26 Oct 2026.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

ProductAffectedFixed in
Ubuntu 25.10linux-azure-fdepkg:deb/ubuntu/linux-azure-fde?arch=source&distro=questingOther threatsAffected
  • 6.17.0-1003.3 – 6.17.0-1017.17
10 affected builds
Fixed in–
Ubuntu 24.04 LTSlinuxpkg:deb/ubuntu/linux?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-86.87
Fixed in
  • 6.8.0-86.87
Ubuntu 24.04 LTSlinux-awspkg:deb/ubuntu/linux-aws?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1041.43
Fixed in
  • 6.8.0-1041.43
Ubuntu 24.04 LTSlinux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1041.47
Fixed in
  • 6.8.0-1041.47
Ubuntu 24.04 LTSlinux-azure-6.11pkg:deb/ubuntu/linux-azure-6.11?arch=source&distro=nobleOther threatsAffected
  • <6.11.0-1018.18~24.04.1
Fixed in
  • 6.11.0-1018.18~24.04.1
Ubuntu 24.04 LTSlinux-azure-nvidiapkg:deb/ubuntu/linux-azure-nvidia?arch=source&distro=nobleOther threatsAffected
  • <6.8.0-1029.32
Fixed in
  • 6.8.0-1029.32

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 should be applied by updating the Linux kernel to one of the fixed versions listed (e.g., 5.4.0-1147.157 and later). The vendor advisory from Ubuntu confirms the availability of fixes in multiple kernel releases. After updating, a system reboot is required. Additionally, recompilation and reinstallation of third-party kernel modules may be necessary due to ABI changes. No alternative mitigations are indicated by the vendor advisory.

Description

CVE-2025-22021 is a critical vulnerability in the Linux kernel's netfilter subsystem affecting IPv6 SNAT packet handling. The flaw is due to a missing connection tracking lookup in the IPv6 socket matching function, causing socket matching to fail for SNATed IPv6 packets. This impacts environments like Kubernetes clusters using IPv6 SNAT and transparent sockets, where packets may not be correctly matched and redirected. The vulnerability has been fixed in multiple Linux kernel versions starting from 5.4.0-1147.157 and related releases.

References

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