Bug 2517057 (CVE-2026-74521) - CVE-2026-74521 kernel: ksmbd: use memcmp() to compare ClientGUIDs
Summary: CVE-2026-74521 kernel: ksmbd: use memcmp() to compare ClientGUIDs
Keywords:
Status: NEW
Alias: CVE-2026-74521
Product: Security Response
Classification: Other
Component: vulnerability
Version: unspecified
Hardware: All
OS: Linux
medium
medium
Target Milestone: ---
Assignee: Product Security DevOps Team
QA Contact:
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2026-08-15 12:47 UTC by OSIDB Bzimport
Modified: 2026-08-19 17:34 UTC (History)
2 users (show)

Fixed In Version:
Clone Of:
Environment:
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Embargoed:


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Description OSIDB Bzimport 2026-08-15 12:47:17 UTC
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.

Comment 1 Mauro Matteo Cascella 2026-08-19 17:29:45 UTC
Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081544-CVE-2026-74521-7ade@gregkh/T


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