Bug 2540184 (CVE-2026-93210)

Summary:	CVE-2026-93210 kernel: smb: client: harden DFS cache against invalid target hints
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	low	Docs Contact:
Priority:	low
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:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's Server Message Block (SMB) client Distributed File System (DFS) cache. This vulnerability occurs due to improper handling of invalid target hints, specifically when a null pointer is dereferenced within the `dfs_cache_noreq_update_tgthint()` function. An attacker could potentially trigger a system crash, leading to a denial of service (DoS).	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 2026-09-24 15:22:01 UTC

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

smb: client: harden DFS cache against invalid target hints

Currently, get_tgt_name() returns ERR_PTR(-ENOENT) when ce->tgthint is
NULL, and dfs_cache_noreq_update_tgthint() assumes ce->tgthint is always
valid.

In preparation for clearing ce->tgthint in free_tgts(), harden callers
of get_tgt_name() against ERR_PTR results and harden
dfs_cache_noreq_update_tgthint() against NULL pointer dereferences.

Comment 1 Mauro Matteo Cascella 2026-09-25 08:21:57 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-93210.mbox