Bug 2536511 (CVE-2026-90215)

Summary:	CVE-2026-90215 kernel: mtd: ubi: Release device reference on busy detach
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security <prodsec-ir-bot>
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 Unsorted Block Images (UBI) subsystem. When a UBI device is busy and `ubi_detach_mtd_dev()` is called, a device reference is not properly released. This oversight prevents the device object from being freed later, potentially leading to a resource leak. An attacker could exploit this to cause a denial of service by exhausting system resources.	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 2026-09-17 18:14:51 UTC

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

mtd: ubi: Release device reference on busy detach

ubi_detach_mtd_dev() obtains a device reference through ubi_get_device()
before checking whether the UBI device is busy. The busy return path drops
ubi->ref_count but leaves the device reference held, so the device object
cannot be released after a later detach.

Drop the device reference before returning -EBUSY.

Comment 1 Mauro Matteo Cascella 2026-09-24 12:32:37 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90215.mbox