Bug 2466987 (CVE-2026-43107)

Summary:	CVE-2026-43107 kernel: xfrm: account XFRMA_IF_ID in aevent size calculation
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:	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 subsystem. A remote attacker could send a specially crafted netlink message that, due to an incorrect size calculation when handling XFRMA_IF_ID attributes, would lead to a buffer overflow. This issue could cause a kernel panic, resulting in a Denial of Service (DoS) for the affected system.	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 2026-05-06 10:01:58 UTC

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

xfrm: account XFRMA_IF_ID in aevent size calculation

xfrm_get_ae() allocates the reply skb with xfrm_aevent_msgsize(), then
build_aevent() appends attributes including XFRMA_IF_ID when x->if_id is
set.

xfrm_aevent_msgsize() does not include space for XFRMA_IF_ID. For states
with if_id, build_aevent() can fail with -EMSGSIZE and hit BUG_ON(err < 0)
in xfrm_get_ae(), turning a malformed netlink interaction into a kernel
panic.

Account XFRMA_IF_ID in the size calculation unconditionally and replace
the BUG_ON with normal error unwinding.

Comment 1 Alexander B 2026-05-06 15:06:54 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050623-CVE-2026-43107-dc43@gregkh/T