What’s Vulnerable › Vulnerabilities

CVE-2026-74521: ksmbd: use memcmp() to compare ClientGUIDs

• Severity: critical (CVSS 9.1 v3.1)
• Exploited in the wild: not listed in CISA KEV
• EPSS: 0.4% probability of exploitation in the next 30 days
• Public exploit or detection template: none known
• Published: 2026-08-15 · updated 2026-10-03

Description

In the Linux kernel, the following vulnerability has been resolved: ksmbd: use memcmp() to compare ClientGUIDs ClientGUID is a fixed-size binary value and can contain embedded NUL bytes. strncmp() stops comparing at the first NUL byte, so different ClientGUID values can incorrectly be treated as equal. Use memcmp() in SMB3 multichannel session binding and FSCTL_VALIDATE_NEGOTIATE_INFO to compare all SMB2_CLIENT_GUID_SIZE bytes.

Affected products

• Linux kernel: 5.15 — fixed in 7.2

How to fix

Upgrade to a fixed version: Linux kernel 7.2. Check the vendor advisory for mitigations.

References

• https://git.kernel.org/stable/c/5a0367bf5ce420be7b19936def2e90adcf32a683
• https://git.kernel.org/stable/c/7bde6f181fa307d2cc1ec2b0313ac8e9811c8232
• https://git.kernel.org/stable/c/a386c83043015a703e227775f778e40343f45911
• https://git.kernel.org/stable/c/ba2a5b66f1d414eb8403d655f8813783892cfc85
• https://git.kernel.org/stable/c/d535363299822c5caa543787b21bd5cfa3e41949
• https://git.kernel.org/stable/c/e8bb506e6ef749ac0336f3e579d8d02396b7d832

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