Bug 2461759 (CVE-2026-31685)

Summary:	CVE-2026-31685 kernel: netfilter: ip6t_eui64: reject invalid MAC header for all packets
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 component. This vulnerability occurs because the `eui64_mt6()` function, which processes IPv6 packets, does not properly validate the MAC header for all packets. Specifically, packets with a zero fragment offset could bypass an existing guard, allowing the system to attempt to access an invalid MAC header. A remote attacker could exploit this by sending specially crafted IPv6 packets, potentially causing a system crash and leading to a Denial of Service (DoS).	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 09:01:41 UTC

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

netfilter: ip6t_eui64: reject invalid MAC header for all packets

`eui64_mt6()` derives a modified EUI-64 from the Ethernet source address
and compares it with the low 64 bits of the IPv6 source address.

The existing guard only rejects an invalid MAC header when
`par->fragoff != 0`. For packets with `par->fragoff == 0`, `eui64_mt6()`
can still reach `eth_hdr(skb)` even when the MAC header is not valid.

Fix this by removing the `par->fragoff != 0` condition so that packets
with an invalid MAC header are rejected before accessing `eth_hdr(skb)`.

Comment 1 Alexander B 2026-04-27 10:24:39 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042545-CVE-2026-31685-3fcc@gregkh/T

Comment 3 errata-xmlrpc 2026-05-28 01:19:56 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10

Via RHSA-2026:21557 https://access.redhat.com/errata/RHSA-2026:21557

Comment 4 errata-xmlrpc 2026-05-28 01:24:02 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9

Via RHSA-2026:21556 https://access.redhat.com/errata/RHSA-2026:21556

Comment 5 errata-xmlrpc 2026-05-28 08:26:01 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:21706 https://access.redhat.com/errata/RHSA-2026:21706

Comment 6 errata-xmlrpc 2026-05-28 13:26:26 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8

Via RHSA-2026:21745 https://access.redhat.com/errata/RHSA-2026:21745

Comment 7 errata-xmlrpc 2026-06-04 10:22:40 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:23237 https://access.redhat.com/errata/RHSA-2026:23237

Comment 8 errata-xmlrpc 2026-06-04 12:16:36 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:23224 https://access.redhat.com/errata/RHSA-2026:23224

Comment 9 errata-xmlrpc 2026-06-08 03:03:28 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:24343 https://access.redhat.com/errata/RHSA-2026:24343

Comment 10 errata-xmlrpc 2026-06-10 17:36:25 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7 Extended Lifecycle Support

Via RHSA-2026:25095 https://access.redhat.com/errata/RHSA-2026:25095

Comment 11 errata-xmlrpc 2026-06-12 19:51:44 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On
  Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support

Via RHSA-2026:25533 https://access.redhat.com/errata/RHSA-2026:25533

Comment 12 errata-xmlrpc 2026-06-17 01:13:57 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:26462 https://access.redhat.com/errata/RHSA-2026:26462

Comment 13 errata-xmlrpc 2026-06-17 06:33:35 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:26515 https://access.redhat.com/errata/RHSA-2026:26515

Comment 14 errata-xmlrpc 2026-06-17 09:18:41 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support
  Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On

Via RHSA-2026:26535 https://access.redhat.com/errata/RHSA-2026:26535

Comment 15 errata-xmlrpc 2026-06-17 11:58:29 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 8.8 Update Services for SAP Solutions
  Red Hat Enterprise Linux 8.8 Telecommunications Update Service

Via RHSA-2026:26563 https://access.redhat.com/errata/RHSA-2026:26563