CVE-2026-68123
Publication date 10 August 2026
Last updated 9 October 2026
Ubuntu priority
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.
Patch details
| Package | Patch details |
|---|
Severity score breakdown
CVSS version: CVSS v3.0
Base score
9.8 · Critical
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
References
Related Ubuntu Security Notices (USN)
- USN-8781-1
- Linux kernel (NVIDIA Tegra) vulnerabilities
- 18 September 2026
- USN-8876-1
- Linux kernel (Azure CVM) vulnerabilities
- 6 October 2026
- USN-8878-1
- Linux kernel (GCP) vulnerabilities
- 6 October 2026
- USN-8879-1
- Linux kernel (Oracle) vulnerabilities
- 6 October 2026
- USN-8877-1
- Linux kernel (GCP) vulnerabilities
- 6 October 2026
- USN-8875-1
- Linux kernel vulnerabilities
- 6 October 2026
- USN-8888-1
- Linux kernel (Azure) vulnerabilities
- 6 October 2026
- USN-8889-1
- Linux kernel (OEM) vulnerabilities
- 6 October 2026
- USN-8887-1
- Linux kernel vulnerabilities
- 6 October 2026
- USN-8887-2
- Linux kernel (AWS) vulnerabilities
- 8 October 2026
- USN-8888-2
- Linux kernel (Azure) vulnerabilities
- 8 October 2026
- USN-8875-2
- Linux kernel (NVIDIA) vulnerabilities
- 9 October 2026
- USN-8887-3
- Linux kernel vulnerabilities
- 9 October 2026
Other references
- https://www.cve.org/CVERecord?id=CVE-2026-68123
- https://git.kernel.org/stable/c/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc
- https://git.kernel.org/stable/c/100a23b1613e9218e0af654ef102352c713f0263
- https://git.kernel.org/stable/c/a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855
- https://git.kernel.org/stable/c/ea85dbcbe8d4056ecb54352f97743d138ea4c407
- https://git.kernel.org/stable/c/4032f8ed10fcb84d41c508dfb04be96589f78dfe