Linux Kernel up to 6.12.96/6.18.39/7.1.4 vhost drivers/vhost/net.c vhost_get_avail_idx comparison

CVSS Meta Temp Score
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CTI Interest Score
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6.2$0-$5k0.47

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.96/6.18.39/7.1.4. It has been classified as critical. This impacts the function vhost_get_avail_idx of the file drivers/vhost/net.c of the component vhost. The manipulation leads to comparison. This vulnerability is documented as CVE-2026-74356. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.12.96/6.18.39/7.1.4. It has been rated as critical. This issue affects the function vhost_get_avail_idx of the file drivers/vhost/net.c of the component vhost. The manipulation with an unknown input leads to a comparison vulnerability. Using CWE to declare the problem leads to CWE-697. The product compares two entities in a security-relevant context, but the comparison is incorrect, which may lead to resultant weaknesses. Impacted is availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: vhost: fix vhost_get_avail_idx for a non empty ring vhost_get_avail_idx is supposed to report whether it has updated vq->avail_idx. Instead, it returns whether all entries have been consumed, which is usually the same. But not always - in drivers/vhost/net.c and when mergeable buffers have been enabled, the driver checks whether the combined entries are big enough to store an incoming packet. If not, the driver re-enables notifications with available entries still in the ring. The incorrect return value from vhost_get_avail_idx propagates through vhost_enable_notify and causes the host to livelock if the guest is not making progress, as vhost will immediately disable notifications and retry using the available entries. This goes back to commit d3bb267bbdcb ("vhost: cache avail index in vhost_enable_notify()") which changed vhost_enable_notify() to compare the freshly read avail index against vq->last_avail_idx instead of the previously cached vq->avail_idx. Commit 7ad472397667 ("vhost: move smp_rmb() into vhost_get_avail_idx()") then carried over the same comparison when refactoring vhost_enable_notify() to call the unified vhost_get_avail_idx(). The obvious fix is to make vhost_get_avail_idx do what the comment says it does and report whether new entries have been added.

It is possible to read the advisory at git.kernel.org. The identification of this vulnerability is CVE-2026-74356 since 08/15/2026. The exploitation is known to be easy. The attack may be initiated remotely. Technical details of the vulnerability are known, but there is no available exploit. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 08/15/2026).

Upgrading to version 6.12.97, 6.18.40, 7.1.5 or 7.2-rc1 eliminates this vulnerability. Applying the patch e115471008111f894c6528d9ab2ce7d0ce306f35/7f229d27bf27c7e589eca690d8612763a7a4801f/a9326b652bc7acd748d7a1143573845c7924d847/09861858a68342f851f71c669ac0f69865c32151 is able to eliminate this problem.

Be aware that VulDB is the high quality source for vulnerability data.

Productinfo

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Vendor

Name

Version

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Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.2

VulDB Base Score: 6.5
VulDB Temp Score: 6.2
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Comparison
CWE: CWE-697
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
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 6.12.97/6.18.40/7.1.5/7.2-rc1
Patch: e115471008111f894c6528d9ab2ce7d0ce306f35/7f229d27bf27c7e589eca690d8612763a7a4801f/a9326b652bc7acd748d7a1143573845c7924d847/09861858a68342f851f71c669ac0f69865c32151

Timelineinfo

08/15/2026 Advisory disclosed
08/15/2026 +0 days CVE reserved
08/15/2026 +0 days VulDB entry created
08/15/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-74356 (🔒)
GCVE (CVE): GCVE-0-2026-74356
GCVE (VulDB): GCVE-100-390311

Entryinfo

Created: 08/15/2026 09:46
Changes: 08/15/2026 09:46 (60)
Complete: 🔍
Cache ID: 216::103

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