Bug 2532170 (CVE-2026-80996)

Summary:	CVE-2026-80996 kernel: net: l2tp: do not propagate multicast notification errors
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 L2TP (Layer 2 Tunneling Protocol) networking component. Specifically, the netlink handlers responsible for creating and modifying L2TP tunnels and sessions may fail to propagate multicast notification errors. This can lead to calling applications retrying operations that have already successfully completed, potentially causing an accumulation of live objects. Such an accumulation could result in resource exhaustion, leading to a denial of service.	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 2026-09-11 21:05:24 UTC

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

net: l2tp: do not propagate multicast notification errors

The tunnel create, tunnel modify, session create, and session modify
netlink handlers send multicast notifications through helpers that can fail
while allocating or encoding a message, or while multicasting it.

For tunnel and session create/modify, a notification is sent after the live
operation has completed. Returning a best-effort notification error as the
command result can therefore report failure for an operation that already
committed and can cause callers to retry and accumulate live objects.

Keep sending notifications for listener visibility, but do not propagate
their best-effort status as the command result. This also keeps the tunnel
modify command consistent with the other notification-only paths.

Comment 1 Keith Grant 2026-09-14 20:07:09 UTC

Upstream advisory:
https://git.kernel.org/pub/scm/linux/security/vulns.git/plain/cve/published/2026/CVE-2026-80996.mbox