CVE-2026-23254

Medium

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().

Package Linux Kernel
Published 2026-03-18
Last modified 2026-06-01
CVSS version 3.1
Patch available
Yes

CVSS 3.1 score

5.5

out of 10
Medium
Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
Low
Integrity
None
Availability
High
Vector string
CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H

Affected versions

Linux kernel versions 6.6.31, 6.8.10, 6.9 and later are affected. Fixed in 6.6.124, 6.12.70, 6.18.10, 6.19 and their respective stable series.

Affected from
≥ 6.6.31 ≥ 6.8.10 ≥ 6.9
Fixed in
✓ 6.6.124 6.6.x ✓ 6.12.70 6.12.x ✓ 6.18.10 6.18.x ✓ 6.19

References

The following references provide additional information about CVE-2026-23254 including vendor advisories, patch commits, exploit details, and third-party analysis. Links are sourced from the NIST NVD database.

4 patch commits total View all on NVD

Frequently asked questions

  • What is CVE-2026-23254?

    CVE-2026-23254 is a Medium severity Linux kernel vulnerability with a CVSS score of 5.5 out of 10 . It affects Linux kernel versions from 6.6.31 onward and has been patched in 6.6.124, 6.12.70, 6.18.10 and others. CVE-2026-23254 has not been confirmed as actively exploited and is not listed in the CISA KEV catalog.

  • What is the CVSS score for CVE-2026-23254?

    CVE-2026-23254 has a CVSS score of 5.5 out of 10, rated Medium severity (CVSS 3.1). The vector string is CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H .

  • Is there a patch available for CVE-2026-23254?

    Yes — CVE-2026-23254 has been patched. Fixed versions include 6.6.124, 6.12.70, 6.18.10 and others. If you are running Linux kernel 6.6.31 or later up to the fix versions, apply the relevant patch for your kernel branch.

  • Is CVE-2026-23254 actively exploited?

    No — CVE-2026-23254 has not been confirmed as actively exploited. It is not listed in the CISA Known Exploited Vulnerabilities (KEV) catalog.

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