Linux Kernel up to 7.2-rc4 openvswitch queue_userspace_packet cutlen off-by-one

CVSS Meta Temp Score
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CTI Interest Score
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9.6$5k-$25k0.00

Summaryinfo

A vulnerability identified as very critical has been detected in Linux Kernel up to 6.6.147/6.12.100/6.18.41/7.1.5/7.2-rc4. This impacts the function queue_userspace_packet of the component openvswitch. The manipulation of the argument cutlen leads to off-by-one. This vulnerability is listed as CVE-2026-68123. The attack may be initiated remotely. There is no available exploit. You should upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.6.147/6.12.100/6.18.41/7.1.5/7.2-rc4 and classified as very critical. This issue affects the function queue_userspace_packet of the component openvswitch. The manipulation of the argument cutlen with an unknown input leads to a off-by-one vulnerability. Using CWE to declare the problem leads to CWE-193. A product calculates or uses an incorrect maximum or minimum value that is 1 more, or 1 less, than the correct value. Impacted is confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at git.kernel.org. The identification of this vulnerability is CVE-2026-68123 since 07/30/2026. The exploitation is known to be easy. The attack may be initiated remotely. No form of authentication is needed for a successful exploitation. Technical details are known, but no exploit is available. The price for an exploit might be around USD $5k-$25k at the moment (estimation calculated on 08/22/2026).

Upgrading to version 6.6.148, 6.12.101, 6.18.42, 7.1.6 or 7.2-rc5 eliminates this vulnerability. Applying the patch a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc/100a23b1613e9218e0af654ef102352c713f0263/ea85dbcbe8d4056ecb54352f97743d138ea4c407/4032f8ed10fcb84d41c508dfb04be96589f78dfe is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

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CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 9.9
VulDB Meta Temp Score: 9.6

VulDB Base Score: 10.0
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 9.8
CNA Vector (Linux): 🔒

CVSSv2info

AVACAuCIA
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Off-by-one
CWE: CWE-193 / CWE-189
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Kernel 6.6.148/6.12.101/6.18.42/7.1.6/7.2-rc5
Patch: a16eaaf7c0b0ccdef6166707d90ffbc6eebf6855/fbfa3ad2ad6f3a5624aba5211c46290fb98cc9dc/100a23b1613e9218e0af654ef102352c713f0263/ea85dbcbe8d4056ecb54352f97743d138ea4c407/4032f8ed10fcb84d41c508dfb04be96589f78dfe

Timelineinfo

07/30/2026 CVE reserved
08/10/2026 +11 days Advisory disclosed
08/10/2026 +0 days VulDB entry created
08/22/2026 +12 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-68123 (🔒)
GCVE (CVE): GCVE-0-2026-68123
GCVE (VulDB): GCVE-100-387473

Entryinfo

Created: 08/10/2026 15:03
Updated: 08/22/2026 23:18
Changes: 08/10/2026 15:03 (60), 08/22/2026 23:18 (11)
Complete: 🔍
Cache ID: 216::103

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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