Bug 2536288 (CVE-2026-90114)

Summary:	CVE-2026-90114 kernel: net: bridge: Reject descending VLAN tunnel ranges
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:
Fixed In Version:		Doc Type:	---
Doc Text:	A flaw was found in the Linux kernel's networking bridge component. When processing specially crafted VLAN (Virtual Local Area Network) tunnel ranges, a logic error can occur where descending VLAN and tunnel IDs are incorrectly handled. This can lead to an unpredictable return value, potentially causing system instability or a denial of service (DoS) condition.	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 17:16:20 UTC

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

net: bridge: Reject descending VLAN tunnel ranges

A pair of descending VLAN and tunnel IDs can pass the tunnel range span
check. The VLAN subtraction produces a negative int, which is converted
to unsigned when compared with the u32 tunnel ID subtraction. It can
therefore equal the wrapped tunnel ID delta.

The range loop then performs no iterations. Since the batched
notification handling added a post-loop error check, this leaves err
uninitialized and makes the request's return value unpredictable.

Reject descending VLAN ranges before comparing the spans. Valid
ascending and single-entry ranges remain unchanged, while malformed
descending ranges consistently return -EINVAL.

This issue was found by a static analysis checker and confirmed by
manual source review.

Comment 1 Keith Grant 2026-09-23 12:30:30 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-90114.mbox