SB20260727174 - Use-after-free in Linux kernel smb client

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Main Vulnerability Database SB20260727174

SB20260727174 - Use-after-free in Linux kernel smb client

Published: July 27, 2026

Security Bulletin ID SB20260727174
CSH Severity
Low
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Local access
Highest impact Denial of service

Breakdown by Severity

Low 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Use-after-free (CVE-ID: CVE-2026-64401)

CWE-ID: CWE-416 - Use After Free

CVSSv4: 5.7 [CVSS:4.0/AV:L/AC:L/AT:P/PR:L/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to a use-after-free in the SMB client witness notification handling in fs/smb/client/cifs_swn.c when processing witness notifications for shared registrations. A local user can trigger notification handling involving a freed tcon pointer to cause a denial of service.

Exploitation requires a same-share second mount so that a registration remains live after the first tcon is unregistered and freed.


Remediation

Install update from vendor's website.

References