Bug 2461758 (CVE-2026-31674)

Summary:	CVE-2026-31674 kernel: netfilter: ip6t_rt: reject oversized addrnr in rt_mt6_check()
Product:	[Other] Security Response	Reporter:	OSIDB Bzimport <bzimport>
Component:	vulnerability	Assignee:	Product Security DevOps Team <prodsec-dev>
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 netfilter subsystem, specifically within the ip6t_rt module. This vulnerability occurs when processing IPv6 routing header (RT) match rules with an oversized address number (addrnr). A local attacker could exploit this by crafting a malicious netfilter rule, leading to an out-of-bounds memory access. This could result in a denial of service, causing the system to crash or become unresponsive.	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 2026-04-25 09:01:37 UTC

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

netfilter: ip6t_rt: reject oversized addrnr in rt_mt6_check()

Reject rt match rules whose addrnr exceeds IP6T_RT_HOPS.

rt_mt6() expects addrnr to stay within the bounds of rtinfo->addrs[].
Validate addrnr during rule installation so malformed rules are rejected
before the match logic can use an out-of-range value.

Comment 1 Alexander B 2026-04-27 10:42:13 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042543-CVE-2026-31674-7e8a@gregkh/T