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.
References8
- git.kernel.org/stable/c/100a23b1613e9218e0af654ef102352c713f0263
- git.kernel.org/stable/c/2623c48cc3a8da9a1886fd8f65c0e348f4406fd6
- git.kernel.org/stable/c/4032f8ed10fcb84d41c508dfb04be96589f78dfe
- git.kernel.org/stable/c/50a6a85f3d6b1d22d8436848606cdef5d2c490b4
- git.kernel.org/stable/c/a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855
- git.kernel.org/stable/c/e211b081901ffca76674082c73eeaed53524c369
- git.kernel.org/stable/c/ea85dbcbe8d4056ecb54352f97743d138ea4c407
- git.kernel.org/stable/c/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc
Metrics
- CVSS 3.1
-
9.8
CRITICAL
Score source: CNA
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H - EPSS — exploit probability
- 1% percentile: 47 · as of 12 November 2026
- CWE
- CWE-191
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