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CVSS 9.8 · CRITICAL

CVE-2026-68123Vulnerabilidad crítica en Open vSwitch del kernel Linux

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.

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Análisis

A critical vulnerability was discovered in the Linux kernel Open vSwitch component. An underflow when handling packet truncation could lead to memory corruption or out-of-bounds access via crafted network traffic, impacting systems that rely on OVS for software-defined networking or container orchestration.

Roles relevantes

LinuxBackendCyberSecurityCloudKubernetesDocker

Severidad

Puntaje: 9.8(CRITICAL)
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
AV: NETWORK
AC: LOW
PR: NONE
UI: NONE
S: UNCHANGED
C: HIGH
I: HIGH
A: HIGH

EPSS

Probabilidad de explotación (próx. 30 días): 0.0018 (0.2%)
Percentil: 7.2%
EPSS: 2026-08-13

Descripción técnica

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.

Publicada: 10/8/2026, 13:19:57
Última modificación: 13/8/2026, 23:17:17

Referencias

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