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Vulnerabilities

Vulnerability · CVE-2026-68123

openvswitch: fix GSO userspace truncation underflow

Published Aug 10, 2026 · catalog updated Oct 15, 2026 · openvswitch: fix GSO userspace

Check if you run it

No confirmed exploitation is on record for CVE-2026-68123. EPSS is 0.55%. Act only if a listed version of openvswitch: fix GSO userspace is installed.

Gaps on this record

  • The stored product name is a package slug. The name on this page is taken from the title (openvswitch: fix GSO userspace).
  • No vendor fix or required action is stored. Compare the linked advisory before you change production.
Severity
Critical9.8
Known exploitation
Not in CISA/VulnCheck KEV
EPSS
0.55%
Remediation
Not established
Affected products
Linux Kernel

In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix GSO userspace truncation underflow OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb length in OVS_CB(skb)->cutlen. When a later userspace action segments a GSO skb, queue_gso_packets() reuses that delta for each smaller segment. A segment can then reach queue_userspace_packet() with cutlen greater than skb->len, underflowing the length passed to skb_zerocopy(). Store the maximum preserved length instead and bound each consumer against the current skb length. Use U32_MAX as the no-truncation sentinel so the value remains valid if skb geometry changes before a consumer handles it.

Are you affected?

Enter the version you run. The result uses only the ranges stored on this record.

The check returns affected, not affected, or incomplete. It does not guess a version that is missing from the record.

  • Linux Kernel4.8.0 → 5.10.265

How to fix CVE-2026-68123

What to do

Three questions, each answered from this record only. Confirm the vendor advisory before you patch.

Should you patch?

No confirmed exploitation is on record for CVE-2026-68123. EPSS is 0.55%. Act only if a listed version of openvswitch: fix GSO userspace is installed.

Which versions are affected?

Compare what you have installed with Kernel 4.8.0 → 5.10.265. Compare the installed version with the linked vendor advisory before you change production.

What should an analyst verify?

No weakness class is stored. EPSS 0.55%. There is no CISA KEV listing. No Exploit-DB or Metasploit reference is linked. Use the source links for the original advisory.

Code

The project this record applies to. Exploit listings stay in References.

Timeline

Detection, updates, and resolution for this record.

  1. Aug 10, 2026 · Catalog

    Detected

    In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix GSO userspace truncation underflow OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb length in OVS_CB(skb)->cutlen. When a later userspace action segments a GSO skb, queue_gso_packets() reuses that delta for each smaller segment. A segment can then reach queue_userspace_packet() with cutlen grea

  2. Oct 13, 2026 · Catalog

    Fix available

    Linux Kernel 4.8.0 → 5.10.265

  3. Oct 13, 2026 · Catalog

    Updated

    In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix GSO userspace truncation underflow OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb length in OVS_CB(skb)->cutlen. When a later userspace action segments a GSO skb, queue_gso_packets() reuses that delta for each smaller segment. A segment can then reach queue_userspace_packet() with cutlen grea

  4. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    Kernel fixed in 5.10.265

  5. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Fix available

    Kernel fixed in 5.10.265

  6. Oct 15, 2026 · OpenSSF OSV / OSV Scanner

    Updated

    In the Linux kernel, the following vulnerability has been resolved: openvswitch: fix GSO userspace truncation underflow OVS_ACTION_ATTR_TRUNC currently stores a delta from the original skb length in OVS_CB(skb)->cutlen. When a later userspace action segments a GSO skb, queue_gso_packets() reuses that delta for each smaller segment. A segment can then reach queue_userspace_packet() with cutlen grea

Sources

References

Freshness

Last verified in this catalog Oct 18, 2026. Significant claims (KEV, EPSS, CVSS, affected ranges) come from the source rows above — open the original publisher for the authoritative advisory.