VulnerabilityPublished 24 Sep 2026Updated 30 Oct 2026

CVE-2026-93829: Linux kernel · smb: client: fix races in cifsd thread creation

Affects Linux kernelSource CVE Database V5

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Not known to be exploited · fixed in ee8f811cbac56ffb738b3a73671a9e75b0f56e99 : update Linux kernel when convenient.

Data as of 30 Oct 2026, 13:04 UTC

Severity

Medium

Rated Medium by Threat Radar's AI analysis · CVSS not yet scored by NVD

Thin evidence

One scorer or none

Patch: Available – fixed in ee8f811cbac56ffb738b3a73671a9e75b0f56e99, e8a5cf2ff5a13fefb228f2069e29dd7d8e37185d, cfa09f63e75cf440c9be97d1e73d509bfbb2c2c5 +2

Exploitation evidence

Disclosed: evidence found.
CVE published 24 Sep 2026
Detectable: no evidence on record.
No public nuclei template indexed
Weaponized: no evidence on record.
No public exploit code indexed in Metasploit or Exploit-DB
Exploited in the wildExploited: no evidence on record.
Not in CISA KEV and no source reports exploitation
Observed by OffSeq MirageSeen by Mirage: no evidence on record.
No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 30 Oct 2026.

Disclosed: The CVE record is public on cve.org. Its publication is t = 0.
Detectable: A public nuclei template can find exposed instances, for defenders and attackers alike.
Weaponized: A Metasploit exploit module or Exploit-DB entry exists (Metasploit scanner modules do not count), or CISA SSVC or the CVSS exploit maturity reports a public proof of concept.
Exploited in the wild: CISA KEV lists it, CISA SSVC rates exploitation active, or a source reports attacks.
Observed by OffSeq Mirage: OffSeq Mirage honeypot sensors recorded attack traffic for this CVE, or found exposed hosts without attack traffic.

Moments are spaced evenly, not to scale; a dashed line marks a gap of six months or more. Deltas count from t = 0. Sources that give only a date (CISA KEV, Exploit-DB, or a time of exactly 00:00Z) read “same day” rather than hours. Metasploit modules carry the flaw’s disclosure date, not their release date, and nuclei templates carry no date, so both appear above but not on the timeline.

What to do

Upgrade to a fixed release listed under Affected software.

Affected software

Product	Affected	Fixed in
LinuxLinux	Affected ≥ aaf737adb6937339494d5a7111f0433cd9676db8, < ee8f811cbac56ffb738b3a73671a9e75b0f56e99	Fixed in ee8f811cbac56ffb738b3a73671a9e75b0f56e99
LinuxLinux	Affected ≥ aaf737adb6937339494d5a7111f0433cd9676db8, < e8a5cf2ff5a13fefb228f2069e29dd7d8e37185d	Fixed in e8a5cf2ff5a13fefb228f2069e29dd7d8e37185d
LinuxLinux	Affected ≥ aaf737adb6937339494d5a7111f0433cd9676db8, < cfa09f63e75cf440c9be97d1e73d509bfbb2c2c5	Fixed in cfa09f63e75cf440c9be97d1e73d509bfbb2c2c5
LinuxLinux	Affected ≥ aaf737adb6937339494d5a7111f0433cd9676db8, < 2376fb3348b4fa72a5158c8a63ff2489e1956541	Fixed in 2376fb3348b4fa72a5158c8a63ff2489e1956541
LinuxLinux	Affected ≥ aaf737adb6937339494d5a7111f0433cd9676db8, < 0eee1e6cddd1d9ce14da06e0238ca8d3362dec90	Fixed in 0eee1e6cddd1d9ce14da06e0238ca8d3362dec90
LinuxLinux	Affected =2.6.22	Fixed in–

AI-suggested

A fix is available and has been applied in the Linux kernel. The patch restructures thread creation to occur after tcp_ses initialization and uses a split kthread_create/wake_up_process approach to prevent race conditions. Users should update to the fixed kernel versions containing the patch commits identified by the provided hashes.

Description

A race condition vulnerability in the Linux kernel's SMB client implementation (cifsd) has been fixed. The issue involved the cifsd demultiplex thread accessing the tcp_ses structure before it was fully initialized by the parent thread, leading to potential unstable behavior. Additionally, the thread creation macro kthread_run could start the thread before the thread pointer was fully set, causing the thread to sleep indefinitely when attempting to exit. The fix involves restructuring thread creation to occur only after tcp_ses is fully populated, using a split kthread_create and wake_up_process approach.

Impact

The vulnerability could lead to unstable kernel behavior due to race conditions in thread creation and access to partially initialized data structures. This may cause kernel threads to sleep indefinitely, potentially impacting system stability or causing denial of service conditions. No public exploits or in-the-wild exploitation are known.

Summary

CVE-2026-93829 addresses race conditions in the Linux kernel's SMB client (cifsd) thread creation process. The vulnerability arises because the cifsd demultiplex thread can access the tcp_ses structure before the parent thread completes its initialization, and because kthread_run may start the thread before returning the thread pointer. This can cause the worker thread to access uninitialized data locklessly and potentially sleep indefinitely waiting for a SIGKILL signal if preempted at a critical moment. The patch moves thread creation to after tcp_ses initialization and changes thread spawning to a two-step process (kthread_create followed by wake_up_process) to ensure safe thread startup.

References

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Exploitation evidence

What to do

Affected software

Description

AI analysisMachine-generated, updated 30 Oct 2026, 12:50 UTC

Technical details

References

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