Linux Kernel up to 6.12.110/6.18.52 cifsd kthread_run race condition

CVSS Meta Temp Score
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CTI Interest Score
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9.5$0-$5k0.00+

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.12.110/6.18.52. It has been classified as very critical. Affected by this issue is the function kthread_run of the component cifsd. Performing a manipulation results in race condition. This vulnerability is known as CVE-2026-93829. Remote exploitation of the attack is possible. No exploit is available. Upgrading the affected component is recommended.

Detailsinfo

A vulnerability, which was classified as very critical, was found in Linux Kernel up to 6.12.110/6.18.52. This affects the function kthread_run of the component cifsd. The manipulation with an unknown input leads to a race condition vulnerability. CWE is classifying the issue as CWE-362. The product contains a code sequence that can run concurrently with other code, and the code sequence requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence that is operating concurrently. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

In the Linux kernel, the following vulnerability has been resolved: smb: client: fix races in cifsd thread creation The cifsd demultiplex thread can run and access tcp_ses before the parent thread has finished populating tcp_ses, which the worker thread accesses locklessly. Also, the kthread_run macro may start the thread before returning the thread pointer. Because the pointer is part of the structure that the thread can access, if the kernel is preempted after the thread is spawned, but before the thread pointer is populated and the thread attempts to exit, it will sleep, waiting for a SIGKILL signal. Fix this by moving creation of the thread to after all of tcp_ses'es fields are populated, and spawning the thread last, using a split kthread_create/wake_up_process logic.

It is possible to read the advisory at git.kernel.org. This vulnerability is uniquely identified as CVE-2026-93829 since 09/18/2026. The exploitability is told to be easy. It is possible to initiate the attack 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 09/24/2026).

Upgrading to version 6.12.111 or 6.18.53 eliminates this vulnerability. Applying the patch ee8f811cbac56ffb738b3a73671a9e75b0f56e99/0eee1e6cddd1d9ce14da06e0238ca8d3362dec90/e8a5cf2ff5a13fefb228f2069e29dd7d8e37185d is able to eliminate this problem. The best possible mitigation is suggested to be upgrading to the latest version.

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

Productinfo

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Version

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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: 9.5

VulDB Base Score: 9.9
VulDB Temp Score: 9.5
VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv2info

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

Exploitinginfo

Class: Race condition
CWE: CWE-362
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 6.12.111/6.18.53
Patch: ee8f811cbac56ffb738b3a73671a9e75b0f56e99/0eee1e6cddd1d9ce14da06e0238ca8d3362dec90/e8a5cf2ff5a13fefb228f2069e29dd7d8e37185d

Timelineinfo

09/18/2026 CVE reserved
09/24/2026 +6 days Advisory disclosed
09/24/2026 +0 days VulDB entry created
09/24/2026 +0 days VulDB entry last update

Sourcesinfo

Vendor: kernel.org

Advisory: git.kernel.org
Status: Confirmed

CVE: CVE-2026-93829 (🔒)
GCVE (CVE): GCVE-0-2026-93829
GCVE (VulDB): GCVE-100-409575

Entryinfo

Created: 09/24/2026 19:23
Changes: 09/24/2026 19:23 (59)
Complete: 🔍
Cache ID: 216::103

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