Bug 2468250 (CVE-2026-43403)

Summary:	CVE-2026-43403 kernel: nsfs: tighten permission checks for ns iteration ioctls
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	medium	Docs Contact:
Priority:	medium
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 `nsfs` component. This vulnerability allows privileged services to bypass permission checks related to namespace iteration input/output controls (ioctls). As a result, one privileged service could potentially view information from other privileged services, leading to unauthorized information disclosure.	Story Points:	---
Clone Of:		Environment:
Last Closed:		Type:	---
Regression:	---	Mount Type:	---
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Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:

Description OSIDB Bzimport 2026-05-08 15:07:02 UTC

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

nsfs: tighten permission checks for ns iteration ioctls

Even privileged services should not necessarily be able to see other
privileged service's namespaces so they can't leak information to each
other. Use may_see_all_namespaces() helper that centralizes this policy
until the nstree adapts.

Comment 1 Keith Grant 2026-05-08 22:14:53 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050840-CVE-2026-43403-3869@gregkh/T