Bug 2516643 (CVE-2026-72463)

Summary:	CVE-2026-72463 kernel: xfrm: Fix dev use-after-free in xfrm async resumption
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
Status:	NEW ---	QA Contact:
Severity:	high	Docs Contact:
Priority:	high
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 xfrm (IP eXtensible FRamework for IPsec) subsystem. This vulnerability occurs during asynchronous resumption where the xfrm_rcv_cb function can modify a network device without properly managing its reference count. This improper handling leads to a use-after-free condition on the tunnel device and a reference count leak on the original device. An attacker could potentially exploit this to cause system instability or a denial of service (DoS).	Story Points:	---
Clone Of:		Environment:
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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 2026-08-15 06:23:33 UTC

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

xfrm: Fix dev use-after-free in xfrm async resumption

xfrm async resumption hold skb->dev refcnt until after transport_finish.
However, xfrm_rcv_cb may modify skb->dev to tunnel dev without taking
device reference, such as vti_rcv_cb. The subsequent async resumption
will decrement the tunnel device's reference count, which lead to uaf
of tunnel dev and refcnt leak of orig dev as below:

unregister_netdevice: waiting for vti1 to become free. Usage count = -2

Stash the original skb->dev to fix refcnt imbalance. The new skb->dev set
by xfrm_rcv_cb can race with device teardown. Extend rcu protection over
xfrm_rcv_cb and transport_finish to prevent races.

Comment 1 Keith Grant 2026-08-19 17:27:23 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026081533-CVE-2026-72463-5eb9@gregkh/T