SB20260727320 - Improper input validation in Linux kernel smb client

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Main Vulnerability Database SB20260727320

SB20260727320 - Improper input validation in Linux kernel smb client

Published: July 27, 2026

Security Bulletin ID SB20260727320
CSH Severity
Medium
Patch available
YES
Number of vulnerabilities 1
Exploitation vector Remote access
Highest impact Partial DoS

Breakdown by Severity

Medium 100%
  • Low
  • Medium
  • High
  • Critical

Description

This security bulletin contains information about 1 vulnerability.


1) Improper input validation (CVE-ID: CVE-2026-64257)

CWE-ID: CWE-20 - Improper input validation

CVSSv4: 6.9 [CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:N/VI:N/VA:L/SC:N/SI:N/SA:N]


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

The vulnerability exists due to improper input validation in __smb2_calc_size() and smb2_check_message() when processing crafted SMB2 responses. A remote attacker can send a specially crafted SMB2 response with overlapping data areas to cause a denial of service.

The issue occurs because an overlapping data area can be misclassified as having no data area, allowing an invalid response to qualify for a length compatibility exception.


Remediation

Install update from vendor's website.

References