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VulnerabilityPublished Updated

CVE-2026-23254: Linux kernel · net: gro: fix outer network offset

Affects Linux kernelSource GCVE Database

0

Mentioned vulnerabilities

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 26 Oct 2026, 12:55 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 1% 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, 6.8.0-1059.65~22.04.1, 6.8.0-1058.65~22.04.1 +30
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 18 Mar 2026

  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 25.10linuxpkg: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-awspkg:deb/ubuntu/linux-aws?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1005.5 – 6.17.0-1019.19
17 affected builds
Fixed in–
Ubuntu 25.10linux-azurepkg:deb/ubuntu/linux-azure?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1004.4 – 6.17.0-1020.20
16 affected builds
Fixed 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 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-oraclepkg:deb/ubuntu/linux-oracle?arch=source&distro=questingOther threatsAffected
  • 6.14.0-1005.5 – 6.17.0-1018.18
16 affected builds
Fixed in–

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

Description

In the Linux kernel, the following vulnerability has been resolved: net: gro: fix outer network offset The udp GRO complete stage assumes that all the packets inserted the RX have the `encapsulation` flag zeroed. Such assumption is not true, as a few H/W NICs can set such flag when H/W offloading the checksum for an UDP encapsulated traffic, the tun driver can inject GSO packets with UDP encapsulation and the problematic layout can also be created via a veth based setup. Due to the above, in the problematic scenarios, udp4_gro_complete() uses the wrong network offset (inner instead of outer) to compute the outer UDP header pseudo checksum, leading to csum validation errors later on in packet processing. Address the issue always clearing the encapsulation flag at GRO completion time. Such flag will be set again as needed for encapsulated packets by udp_gro_complete().

References

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