Bug 2540410 (CVE-2026-93812)

Summary:	CVE-2026-93812 kernel: ksmbd: fix sd_ndr.data memory leak in ksmbd_vfs_set_sd_xattr
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
Version:	unspecified	CC:	akhatavk, aos-team-art-private, asdas, dpaolell, jdelft, jupierce, lgarciaa, mbiarnes, ppalepu, ppostler, prdhamdh, rhel-process-autobot, sghai, sidsharm, suppawar, vlaad, watson-tool-maintainers
Target Milestone:	---	Keywords:	Security
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
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Doc Text:	A flaw was found in the Linux kernel's ksmbd (Server Message Block) server. A remote attacker could cause a denial of service (DoS) by triggering a kernel memory leak during security attribute operations. When an error occurs while encoding security descriptors, dynamically allocated memory is not freed on the failure path, gradually consuming system memory over time.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
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Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-09-24 16:43:23 UTC

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

ksmbd: fix sd_ndr.data memory leak in ksmbd_vfs_set_sd_xattr

ndr_encode_v4_ntacl() allocates sd_ndr.data via kzalloc() at entry.
If any subsequent ndr_write_*() call returns error during encoding,
the allocated sd_ndr.data won't be freed and causes memory leak.

Move kfree(sd_ndr.data) into out label to ensure the buffer gets
released on all success and error return paths.

Comment 1 Mauro Matteo Cascella 2026-09-28 13:30:08 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93812.mbox