CVE-2026-68123 PUBLISHED

openvswitch: fix GSO userspace truncation underflow

Assigner: Linux
Reserved: 30.07.2026 Published: 10.08.2026 Updated: 10.08.2026

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.

Product Status

Vendor Linux
Product Linux
Versions Default: unaffected
  • affected from f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855 (excl.)
  • affected from f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc (excl.)
  • affected from f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to 100a23b1613e9218e0af654ef102352c713f0263 (excl.)
  • affected from f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to ea85dbcbe8d4056ecb54352f97743d138ea4c407 (excl.)
  • affected from f2a4d086ed4c588d32fe9b7aa67fead7280e7bf1 to 4032f8ed10fcb84d41c508dfb04be96589f78dfe (excl.)
Vendor Linux
Product Linux
Versions Default: affected
  • Version 4.8 is affected
  • unaffected from 0 to 4.8 (excl.)
  • unaffected from 6.6.148 to 6.6.* (incl.)
  • unaffected from 6.12.101 to 6.12.* (incl.)
  • unaffected from 6.18.42 to 6.18.* (incl.)
  • unaffected from 7.1.6 to 7.1.* (incl.)
  • unaffected from 7.2-rc5 to * (incl.)

References