CVE-2026-43215Network attack vector

CIFS state corruption via mismatched tcon locking

Published May 6, 2026 · Updated May 6, 2026

Improper locking in the Linux kernel CIFS client in affected 6.x builds allows remote attackers to corrupt tcon reference accounting via SMB traffic. The cached-directory cleanup and cancelled-close paths update tc_count while holding cifs_tcp_ses_lock instead of the tcon-specific tc_lock, allowing concurrent updates to race. Exploitation requires interaction with an attacker-controlled SMB service and user interaction; the CNA reports confidentiality, integrity, and availability impact but does not disclose a specific end state.

CVSS severity8.8
High
EPSS probability0.30%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Improper locking in the Linux kernel CIFS client in affected 6.x builds allows remote attackers to corrupt tcon reference accounting via SMB traffic. The cached-directory cleanup and cancelled-close paths update tc_count while holding cifs_tcp_ses_lock instead of the tcon-specific tc_lock, allowing concurrent updates to race. Exploitation requires interaction with an attacker-controlled SMB service and user interaction; the CNA reports confidentiality, integrity, and availability impact but does not disclose a specific end state.

The record

CVE
CVE-2026-43215
Published
May 6, 2026
Updated
May 6, 2026
Vendor
The Linux Kernel Organization
Product
Linux Kernel
Classifications
CWE-667
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 6, 2026CVE publishedPublication date reported by the CVE source.
  2. May 6, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3969db6b22e3d90d8c5f22ac1a7fe0350a94c136
  2. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <601dd3b79769b38d30b693c40afdb2a4b7edf9d0
  3. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8c59eeeeffa1524ef57e173a89a1a3ff539888d5
  4. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <953953abb66e52c224057ab91e404284fefeab62
  5. Affected versionversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <96c4af418586ee9a6aab61738644366426e05316

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

The Linux Kernel Organization · Linux Kernelversion=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <3969db6b22e3d90d8c5f22ac1a7fe0350a94c136; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <601dd3b79769b38d30b693c40afdb2a4b7edf9d0; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <8c59eeeeffa1524ef57e173a89a1a3ff539888d5; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <953953abb66e52c224057ab91e404284fefeab62; version=1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 <96c4af418586ee9a6aab61738644366426e05316

Published CVSS scores

8.8kernel.orgCVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-667Improper Locking

Public exploit references

No public exploit references are available in this record.

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Technologies

Your stack

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Your stack

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