Bug 2461757 (CVE-2026-31684)

Summary:	CVE-2026-31684 kernel: net: sched: act_csum: validate nested VLAN headers
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 network scheduler component. A remote attacker could send specially crafted network packets containing nested Virtual Local Area Network (VLAN) headers. This could cause the kernel to read beyond allocated memory, leading to a system crash and a denial of service.	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 09:01:33 UTC

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

net: sched: act_csum: validate nested VLAN headers

tcf_csum_act() walks nested VLAN headers directly from skb->data when an
skb still carries in-payload VLAN tags. The current code reads
vlan->h_vlan_encapsulated_proto and then pulls VLAN_HLEN bytes without
first ensuring that the full VLAN header is present in the linear area.

If only part of an inner VLAN header is linearized, accessing
h_vlan_encapsulated_proto reads past the linear area, and the following
skb_pull(VLAN_HLEN) may violate skb invariants.

Fix this by requiring pskb_may_pull(skb, VLAN_HLEN) before accessing and
pulling each nested VLAN header. If the header still is not fully
available, drop the packet through the existing error path.

Comment 1 Alexander B 2026-04-27 10:17:00 UTC

Upstream advisory:
https://lore.kernel.org/linux-cve-announce/2026042545-CVE-2026-31684-6974@gregkh/T

Comment 4 errata-xmlrpc 2026-05-28 01:19:55 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 5 errata-xmlrpc 2026-05-28 01:24:00 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 6 errata-xmlrpc 2026-05-28 08:25:59 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 7 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 8 errata-xmlrpc 2026-07-15 15:54:11 UTC

This issue has been addressed in the following products:

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

Via RHSA-2026:40068 https://access.redhat.com/errata/RHSA-2026:40068

Comment 9 errata-xmlrpc 2026-07-17 12:49:20 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7 Extended Lifecycle Support

Via RHSA-2026:41234 https://access.redhat.com/errata/RHSA-2026:41234

Comment 10 errata-xmlrpc 2026-07-17 13:02:19 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 7 Extended Lifecycle Support

Via RHSA-2026:41235 https://access.redhat.com/errata/RHSA-2026:41235

Comment 11 errata-xmlrpc 2026-07-22 06:23:44 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.4 Update Services for SAP Solutions

Via RHSA-2026:43231 https://access.redhat.com/errata/RHSA-2026:43231

Comment 12 errata-xmlrpc 2026-07-23 11:56:58 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.6 Extended Update Support

Via RHSA-2026:44385 https://access.redhat.com/errata/RHSA-2026:44385

Comment 13 errata-xmlrpc 2026-07-23 20:55:03 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 10.0 Extended Update Support

Via RHSA-2026:44694 https://access.redhat.com/errata/RHSA-2026:44694

Comment 14 errata-xmlrpc 2026-07-29 00:52:04 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:47632 https://access.redhat.com/errata/RHSA-2026:47632

Comment 15 errata-xmlrpc 2026-07-29 01:06:28 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-2026:47633 https://access.redhat.com/errata/RHSA-2026:47633

Comment 16 errata-xmlrpc 2026-07-29 13:30:51 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-2026:47869 https://access.redhat.com/errata/RHSA-2026:47869

Comment 17 errata-xmlrpc 2026-07-29 22:42:23 UTC

This issue has been addressed in the following products:

  Red Hat Enterprise Linux 9.2 Update Services for SAP Solutions

Via RHSA-2026:47739 https://access.redhat.com/errata/RHSA-2026:47739