LiveActive security incident?Get immediate response
CVE Record

CVE-2026-23254: net: gro: fix outer network offset

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().

UnknownCVSS not scoredNot KEV-listedUpdated
Discuss exposureBack to CVEs
Glexia's TakeAutomated analysisunknown

Security readout for executives and security teams

Plain-English summary

This Linux kernel flaw can make certain UDP-encapsulated network traffic fail checksum validation during packet processing. The public record describes packet-processing errors, not code execution or privilege escalation.

Executive priority

Track and patch through normal kernel maintenance unless affected systems handle critical UDP tunnel or virtual networking traffic. Urgency is constrained by missing severity and exploit evidence.

Technical view

During UDP GRO completion, packets with an unexpected encapsulation flag may use the inner network offset instead of the outer offset when computing the UDP pseudo-header checksum. The kernel fix clears the encapsulation flag at GRO completion so it is reset later when needed.

Likely exposure

Exposure appears limited to Linux kernels in the affected ranges where UDP encapsulation, GRO/GSO, NIC checksum offload, tun, or veth-based traffic paths are used. Downstream distribution package status is not provided.

Exploitation context

The bundle does not show KEV listing, active exploitation, public exploit activity, or a CVSS score. The stated consequence is later checksum validation errors in packet processing under specific traffic layouts.

Researcher notes

The record is operationally narrow: GRO completion state handling creates incorrect outer UDP checksum computation. Evidence supports reliability or packet-processing impact, but not confidentiality, integrity, privilege escalation, or remote code execution claims.

Mitigation direction

  • Apply Linux kernel stable updates containing the referenced GRO fixes.
  • Check your Linux distribution advisory for backported package names and fixed kernel builds.
  • Prioritize hosts using UDP encapsulation, virtual networking, tun, veth, or NIC checksum offload.
  • Avoid changing offload settings as a primary fix unless vendor guidance recommends it.

Validation and detection

  • Inventory running kernel versions across Linux hosts and containers with host networking exposure.
  • Map kernel builds to vendor advisories and the CVE record’s affected ranges.
  • Review network workloads using UDP encapsulation, tunnel interfaces, or veth-heavy topologies.
  • Confirm patched kernels include one of the referenced stable commits or distro backports.
Prepared
Confidence
medium
Sources
6

Public sources used

Generated from the cited source records. This long-tail analysis has not been individually reviewed by a named human.

Potential ATT&CK relevance

Conservative CVE-to-ATT&CK context

These mappings and lookup hints may be relevant to the vulnerability behavior, CWE, affected product, or exposure path. Glexia-inferred context is not an official MITRE, ATT&CK, CWE, or CVE Program mapping.

ATT&CK lookup starting points

Use these exact CWE pages and searches to review the Glexia ATT&CK library from this CVE's weakness and description context.

cve · low confidence lookup

CVE-2026-23254 mapping review

Open the CVE-to-ATT&CK bridge for reviewed, inferred, or future official mappings tied to this CVE.

Open ATT&CK lookup
Vulnerability profileCVE Program record
Severity
Unknown
CVSS
Not scored
Known Exploited
No
Published
Official CVE source material

CNA and ADP enrichment extracted from CVE v5

These fields come from the CVE record and ADP containers, not from Glexia's Take. They preserve time-varying source decisions such as CISA SSVC, KEV status, CVSS metrics, and provider references.

0CVSS vectors
3Timeline events
0ADP providers
5Source links

Vulnerability timeline

Timeline events are normalized from CVE metadata, CNA source timelines, ADP timelines, and KEV metadata when present.

  1. CVE reservedCVE Program

    The CVE ID was reserved by the assigning CNA.

  2. CVE publishedCVE Program

    The CVE record was published.

  3. CVE updatedCVE Program

    The CVE record metadata indicates this as the latest update time.

Source materials

Affected products

Products and packages named in the record

VendorProductVersion / packageStatus
LinuxLinuxaf276a5ac8e938c8b058e3e124073cc1e322d98b, 5ef31ea5d053a8f493a772ebad3f3ce82c35d845, 5ef31ea5d053a8f493a772ebad3f3ce82c35d845, 5ef31ea5d053a8f493a772ebad3f3ce82c35d845, dbd9466d323a72e22efe09151253d195d36d3bf6, 6.6.31, 6.8.10unaffected
LinuxLinux6.9, 0, 6.6.124, 6.12.70, 6.18.10, 6.19affected
Weakness

CWE details

No CWE listed

CWE links open Glexia weakness intelligence pages with official CWE context, developer remediation guidance, and related CVE mappings.