SB2026072153 - Improper access control in Linux kernel smb server

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Main Vulnerability Database SB2026072153

SB2026072153 - Improper access control in Linux kernel smb server

Published: July 21, 2026

Security Bulletin ID SB2026072153
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Denial of service

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-2026-53383)

CWE-ID: CWE-284 - Improper Access Control

CVSSv4: 8.7 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:H/SC:N/SI:N/SA:N]


The vulnerability allows a remote attacker to cause a denial of service.

The vulnerability exists due to improper access control in smb2_check_user_session() and the ksmbd compound request handling path when processing a crafted compound SMB request with a non-valid session. A remote attacker can send a specially crafted compound request to cause a denial of service.

By using SESSION_SETUP as the first compound operation and a related TREE_CONNECT request with SessionId set to ULLONG_MAX as the second operation, an in-progress session can reach a NULL pointer dereference because sess->user remains NULL.


Remediation

Install update from vendor's website.

References