CVE-2026-64136

Analyzed Analyzed - Analysis Complete

Race Condition in Linux Kernel SMB Client

Publication date: 2026-07-19

Last updated on: 2026-08-13

Assigner: kernel.org

Description

In the Linux kernel, the following vulnerability has been resolved: smb: client: protect tc_count increment in smb2_find_smb_sess_tcon_unlocked() Commit 96c4af418586 ("cifs: Fix locking usage for tcon fields") refactored cifs code to change cifs_tcp_ses_lock for tc_lock around tc_count changes. There was missing lock around tc_count increment inside smb2_find_smb_sess_tcon_unlocked().

CVSS Scores

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Meta Information

Published

2026-07-19

Last Modified

2026-08-13

Generated

2026-08-29

AI Q&A

2026-07-19

EPSS Evaluated

2026-08-28

NVD

CVE-2026-64136

EUVD

EUVD-2026-45821

Affected Vendors & Products

Vendor	Product	Version / Range
linux	linux_kernel	7.1
linux	linux_kernel	7.1
linux	linux_kernel	7.1
linux	linux_kernel	7.1
linux	linux_kernel	From 6.12.75 (inc) to 6.12.92 (exc)
linux	linux_kernel	From 6.18.16 (inc) to 6.18.34 (exc)
linux	linux_kernel	From 6.19.6 (inc) to 7.0.11 (exc)
linux	linux_kernel	From 6.6.128 (inc) to 6.6.142 (exc)

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-UNKNOWN

Attack-Flow Graph

Executive Summary

This is a Linux kernel vulnerability in the SMB client component. It involves a missing lock around the tc_count increment in the function smb2_find_smb_sess_tcon_unlocked(). The issue was introduced by a previous commit that changed locking mechanisms for tcon fields.

Detection Guidance

This vulnerability involves a race condition in the Linux kernel's SMB client code, specifically in the cifs module. Detection requires checking for kernel versions affected by the missing lock around tc_count increment in smb2_find_smb_sess_tcon_unlocked().

Impact Analysis

This vulnerability could lead to race conditions in the SMB client, potentially causing memory corruption or undefined behavior. This might result in system crashes, data corruption, or unauthorized access to sensitive information.

Compliance Impact

The provided CVE data does not specify any direct impact on compliance with standards like GDPR or HIPAA. The vulnerability involves a locking issue in the Linux kernel's SMB client, which could lead to race conditions but does not explicitly mention data privacy or security compliance implications.

Mitigation Strategies

Update the Linux kernel to a patched version that includes the fix for CVE-2026-64136. Monitor vendor advisories for kernel updates and apply them promptly.

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