Bug 2502495 (CVE-2026-64138)

Summary:	CVE-2026-64138 kernel: ksmbd: validate SID in parent security descriptor during ACL inheritance
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability-draft	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 ksmbd module of the Linux kernel. This vulnerability arises from improper validation of Security Identifiers (SIDs) within the NT Security Descriptor (smb_ntsd) during Access Control List (ACL) inheritance. An attacker could exploit this to bypass intended security restrictions, potentially leading to unauthorized access to resources.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
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oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-07-19 17:02:29 UTC

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

ksmbd: validate SID in parent security descriptor during ACL inheritance

Introduce smb_validate_ntsd_sid() helper to safely validate Owner SID
and Group SID inside the NT Security Descriptor (smb_ntsd) retrieved
from the parent directory.

Comment 1 TEJ RATHI 2026-07-21 07:04:50 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026071928-CVE-2026-64138-e6dd@gregkh/T