SB20260816192 - Incorrect Comparison in Linux kernel smb server
Published: August 16, 2026
Security Bulletin ID
SB20260816192
CSH Severity
Low
Patch available
YES
Number of vulnerabilities
1
Exploitation vector
Remote access
Highest impact
Data manipulation
Breakdown by Severity
- Low
- Medium
- High
- Critical
Description
This security bulletin contains information about 1 vulnerability.
1) Incorrect Comparison (CVE-ID: CVE-2026-74521)
CWE-ID: CWE-697 - Incorrect Comparison
CVSSv4: 5.3 [CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:N/VI:L/VA:N/SC:N/SI:N/SA:N]
The vulnerability allows a remote user to bypass client identity checks.
The vulnerability exists due to improper comparison of fixed-size binary data in ksmbd SMB3 multichannel session binding and FSCTL_VALIDATE_NEGOTIATE_INFO handling when processing ClientGUID values. A remote user can send a crafted ClientGUID containing embedded NUL bytes to bypass client identity checks.
Remediation
Install update from vendor's website.