CVE-2026-74521 and is rated Critical severity with a CVSS score of 9.1. It is not in the current CISA KEV record we collected. That does not prove exploitation has not occurred.
CISA KEVNot listedBased on the latest collected catalog
EPSS0.4%Estimated 30-day exploitation probability
Ransomware useNot markedCISA KEV ransomware field
Threat actors0Source-linked actor relationships
Overview
What is CVE-2026-74521?
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.