Bug 2507278 (CVE-2026-64395)

Summary:	CVE-2026-64395 kernel: ksmbd: require source read access for duplicate extents
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	unspecified	CC:	rhel-process-autobot, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's ksmbd component. This vulnerability allows an attacker with attribute access to a file to bypass security checks when duplicating file extents. By using the FSCTL_DUPLICATE_EXTENTS_TO_FILE function, an attacker can copy the contents of a source file to a destination that they can read, leading to information disclosure.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-07-25 10:14:13 UTC

In the Linux kernel, the following vulnerability has been resolved:

ksmbd: require source read access for duplicate extents

FSCTL_DUPLICATE_EXTENTS_TO_FILE passes the source file directly to
vfs_clone_file_range() or vfs_copy_file_range() without checking the SMB
access mask granted to the source handle. A handle opened with attribute
access can consequently be used to copy file contents into an
attacker-readable destination.

Require FILE_READ_DATA on the source handle before either VFS operation,
matching other ksmbd data-copy paths.

Comment 1 TEJ RATHI 2026-07-27 05:29:07 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026072528-CVE-2026-64395-26a3@gregkh/T