Bug 2464419 (CVE-2026-31738)

Summary:	CVE-2026-31738 kernel: vxlan: validate ND option lengths in vxlan_na_create
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
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Doc Text:	A flaw was found in the Linux kernel's Virtual Extensible LAN (VXLAN) implementation. A remote attacker could exploit this vulnerability by sending specially crafted Neighbor Discovery (ND) options to the `vxlan_na_create` function. This could cause the parser to read beyond the intended memory boundaries or use an incorrectly sized source Link-Layer Address (LLADDR) option payload, potentially leading to memory corruption and system instability or a denial of service.	Story Points:	---
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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 2026-05-01 15:05:49 UTC

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

vxlan: validate ND option lengths in vxlan_na_create

vxlan_na_create() walks ND options according to option-provided
lengths. A malformed option can make the parser advance beyond the
computed option span or use a too-short source LLADDR option payload.

Validate option lengths against the remaining NS option area before
advancing, and only read source LLADDR when the option is large enough
for an Ethernet address.

Comment 1 Keith Grant 2026-05-01 21:33:51 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026050138-CVE-2026-31738-7d4e@gregkh/T