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CVE-2026-68123

CRITICALCVSS 9.8/10EPSS 0.50%

Last modified

CVE-2026-68123 is a critical-severity vulnerability rated 9.8/10 on the CVSS scale. 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. EPSS estimates a 0.50% chance of exploitation in the next 30 days.

Description

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.

Metrics

CVSS 3.1
9.8/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS Probability
0.50%

40.6th percentile

Probability of exploitation in the next 30 days. Learn more

Affected Software

Source: CNA advisory (CVE.org). NVD analysis pending.

VendorProductVersions
LinuxLinux>= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < 50a6a85f3d6b1d22d8436848606cdef5d2c490b4; >= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < 2623c48cc3a8da9a1886fd8f65c0e348f4406fd6; >= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < e211b081901ffca76674082c73eeaed53524c369; >= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855; >= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc; >= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < 100a23b1613e9218e0af654ef102352c713f0263; >= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < ea85dbcbe8d4056ecb54352f97743d138ea4c407; >= f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1, < 4032f8ed10fcb84d41c508dfb04be96589f78dfe
LinuxLinux4.8

References

Timeline

Published
Last Modified
Status
Received

Frequently Asked Questions

What is CVE-2026-68123?
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.
How severe is CVE-2026-68123?
CVE-2026-68123 has a CVSS score of 9.8/10 (CRITICAL severity). The EPSS model estimates a 0.50% probability of exploitation in the next 30 days.
How do I fix CVE-2026-68123?
Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

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Source: NVD / NIST