CVE-2026-68123

openvswitch: fix GSO userspace truncation underflow

State: Published
Severity: 9.8 Critical
Published: Aug 10, 2026
Updated: Oct 19, 2026
Reserved: Jul 30, 2026

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.

Scores

CVSS	Score	Vector	Source
3.1	9.8 Critical	CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H	Linux

Weaknesses

CWE-191 Integer Underflow (Wrap or Wraparound)

Affected Products

Product	Versions
LinuxLinux	f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 50a6a85f3d6b1d22d8436848606cdef5d2c490b4Affected f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 2623c48cc3a8da9a1886fd8f65c0e348f4406fd6Affected f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before e211b081901ffca76674082c73eeaed53524c369Affected f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855Affected f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dcAffected f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 100a23b1613e9218e0af654ef102352c713f0263Affected f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before ea85dbcbe8d4056ecb54352f97743d138ea4c407Affected f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 4032f8ed10fcb84d41c508dfb04be96589f78dfeAffected
LinuxLinux	4.8Affected before 4.8Not affected 5.10.265 through 5.10.Not affected 5.15.216 through 5.15.Not affected 6.1.183 through 6.1.Not affected 6.6.148 through 6.6.Not affected 6.12.101 through 6.12.Not affected 6.18.42 through 6.18.Not affected 7.1.6 through 7.1.*Not affected 7.2 and laterNot affected

Product

Versions

LinuxLinux

f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 50a6a85f3d6b1d22d8436848606cdef5d2c490b4Affected
f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 2623c48cc3a8da9a1886fd8f65c0e348f4406fd6Affected
f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before e211b081901ffca76674082c73eeaed53524c369Affected
f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855Affected
f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dcAffected
f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 100a23b1613e9218e0af654ef102352c713f0263Affected
f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before ea85dbcbe8d4056ecb54352f97743d138ea4c407Affected
f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to before 4032f8ed10fcb84d41c508dfb04be96589f78dfeAffected

LinuxLinux

4.8Affected
before 4.8Not affected
5.10.265 through 5.10.*Not affected
5.15.216 through 5.15.*Not affected
6.1.183 through 6.1.*Not affected
6.6.148 through 6.6.*Not affected
6.12.101 through 6.12.*Not affected
6.18.42 through 6.18.*Not affected
7.1.6 through 7.1.*Not affected
7.2 and laterNot affected

References

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