SB20260727184 - Improper access control in Linux kernel smb server

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Main Vulnerability Database SB20260727184

SB20260727184 - Improper access control in Linux kernel smb server

Published: July 27, 2026

Security Bulletin ID SB20260727184
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Data manipulation

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper access control (CVE-ID: CVE-2026-64394)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: 7.1 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:H/VA:N/SC:N/SI:N/SA:N]


The vulnerability allows a remote user to modify file access control metadata to grant additional access.

The vulnerability exists due to improper access control in smb2_set_info_sec() when handling SMB2_SET_INFO requests with InfoType SMB2_O_INFO_SECURITY. A remote user can send a specially crafted SMB2_SET_INFO request over a handle opened with FILE_WRITE_ATTRIBUTES only to modify file access control metadata to grant additional access.

The issue affects the SECURITY arm of SMB2 SET_INFO, where no per-handle check for FILE_WRITE_DAC or FILE_WRITE_OWNER is performed before rewriting the file's owner or DACL.


Remediation

Install update from vendor's website.

References