ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach()

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Summary

CVECVE-2026-43038
StatePUBLISHED
AssignerLinux
Source PriorityCVE Program / NVD first with legacy fallback
Published2026-05-01 15:16:48 UTC
Updated2026-07-15 02:21:41 UTC
DescriptionIn the Linux kernel, the following vulnerability has been resolved: ipv6: icmp: clear skb2->cb[] in ip6_err_gen_icmpv6_unreach() Sashiko AI-review observed: In ip6_err_gen_icmpv6_unreach(), the skb is an outer IPv4 ICMP error packet where its cb contains an IPv4 inet_skb_parm. When skb is cloned into skb2 and passed to icmp6_send(), it uses IP6CB(skb2). IP6CB interprets the IPv4 inet_skb_parm as an inet6_skb_parm. The cipso offset in inet_skb_parm.opt directly overlaps with dsthao in inet6_skb_parm at offset 18. If an attacker sends a forged ICMPv4 error with a CIPSO IP option, dsthao would be a non-zero offset. Inside icmp6_send(), mip6_addr_swap() is called and uses ipv6_find_tlv(skb, opt->dsthao, IPV6_TLV_HAO). This would scan the inner, attacker-controlled IPv6 packet starting at that offset, potentially returning a fake TLV without checking if the remaining packet length can hold the full 18-byte struct ipv6_destopt_hao. Could mip6_addr_swap() then perform a 16-byte swap that extends past the end of the packet data into skb_shared_info? Should the cb array also be cleared in ip6_err_gen_icmpv6_unreach() and ip6ip6_err() to prevent this? This patch implements the first suggestion. I am not sure if ip6ip6_err() needs to be changed. A separate patch would be better anyway.

Risk And Classification

Primary CVSS: v3.1 7.3 HIGH from ADP

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

EPSS: 0.000530000 probability, percentile 0.164060000 (date 2026-05-05)

Problem Types: NVD-CWE-noinfo | CWE-843 | CWE-843 Access of Resource Using Incompatible Type ('Type Confusion')

VersionSourceTypeScoreSeverityVector
3.1ADPCVSS7.3HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
3.1416baaa9-dc9f-4396-8d5f-8c081fb06d67Secondary9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
3.10b0ca135-0b70-47e7-9f44-1890c2a1c46cSecondary7.3HIGHCVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H
3.1CNADECLARED9.8CRITICALCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

CVSS v3.1 Breakdown

Attack Vector
Local
Attack Complexity
Low
Privileges Required
Low
User Interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
Low
Availability
High

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:L/A:H

NVD Known Affected Configurations (CPE 2.3)

TypeVendorProductVersionUpdateEditionLanguage
Operating System Linux Linux Kernel All All All All

Vendor Declared Affected Products

SourceVendorProductVersionPlatforms
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 c438ba010171b70bad22fc18b1d5bdc3627476e8 git Not specified
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7 git Not specified
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 a4437faf135da293d16fcc4cc607316742bd0ebb git Not specified
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 3d5127d998de617b130aae96b138dba22ac6a8a7 git Not specified
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 e41953e7d118e2702bcb217879c173d9d1d3cd4e git Not specified
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 a2edbb6393972a02114b6003953a5cef3104fada git Not specified
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 1ceeebd5bd6d855b17a5df625109bfe29129d7cf git Not specified
CNA Linux Linux affected ca15a078bd907df5fc1c009477869c5cbde3b753 86ab3e55673a7a49a841838776f1ab18d23a67b5 git Not specified
CNA Linux Linux affected 3.13 Not specified
CNA Linux Linux unaffected 3.13 semver Not specified
CNA Linux Linux unaffected 5.10.253 5.10.* semver Not specified
CNA Linux Linux unaffected 5.15.203 5.15.* semver Not specified
CNA Linux Linux unaffected 6.1.168 6.1.* semver Not specified
CNA Linux Linux unaffected 6.6.134 6.6.* semver Not specified
CNA Linux Linux unaffected 6.12.81 6.12.* semver Not specified
CNA Linux Linux unaffected 6.18.22 6.18.* semver Not specified
CNA Linux Linux unaffected 6.19.12 6.19.* semver Not specified
CNA Linux Linux unaffected 7.0 * original_commit_for_fix Not specified
ADP Red Hat Red Hat Enterprise Linux 10 unaffected 0:6.12.0-211.28.1.el10_2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 10.0 Extended Update Support unaffected 0:6.12.0-55.77.1.el10_0 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 0:4.18.0-553.132.1.rt7.473.el8_10 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8 unaffected 0:4.18.0-553.132.1.el8_10 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.4 Advanced Mission Critical Update Support unaffected 0:4.18.0-305.194.1.el8_4 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.4 Extended Update Support Long-Life Add-On unaffected 0:4.18.0-305.194.1.el8_4 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.6 Advanced Mission Critical Update Support unaffected 0:4.18.0-372.195.1.el8_6 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.6 Extended Update Support Long-Life Add-On unaffected 0:4.18.0-372.195.1.el8_6 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.8 Telecommunications Update Service unaffected 0:4.18.0-477.145.1.el8_8 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 8.8 Update Services For SAP Solutions unaffected 0:4.18.0-477.145.1.el8_8 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9 unaffected 0:5.14.0-687.19.1.el9_8 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:5.14.0-284.174.1.el9_2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.2 Update Services For SAP Solutions unaffected 0:5.14.0-284.174.1.rt14.459.el9_2 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.4 Update Services For SAP Solutions unaffected 0:5.14.0-427.129.1.el9_4 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 9.6 Extended Update Support unaffected 0:5.14.0-570.119.1.el9_6 * rpm Not specified
ADP Red Hat Red Hat Enterprise Linux 6 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 7 Not specified Not specified
ADP Red Hat Red Hat Enterprise Linux 9 Not specified Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIMATIC S7-1500 CPU 1518F-4 PN/DP MFP affected V3.1.5 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.6 * custom Not specified
ADP Siemens SIPLUS S7-1500 CPU 1518-4 PN/DP MFP affected V3.1.5 * custom Not specified

References

ReferenceSourceLinkTags
security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43038.json 0b0ca135-0b70-47e7-9f44-1890c2a1c46c security.access.redhat.com
git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-082556.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
access.redhat.com/errata/RHSA-2026:25120 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:23224 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
access.redhat.com/errata/RHSA-2026:22900 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:24343 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
cert-portal.siemens.com/productcert/html/ssa-019113.html 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e cert-portal.siemens.com
access.redhat.com/errata/RHSA-2026:22940 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
access.redhat.com/errata/RHSA-2026:25533 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:30129 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
bugzilla.redhat.com/show_bug.cgi 0b0ca135-0b70-47e7-9f44-1890c2a1c46c bugzilla.redhat.com
git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
access.redhat.com/errata/RHSA-2026:23237 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e 416baaa9-dc9f-4396-8d5f-8c081fb06d67 git.kernel.org Patch
access.redhat.com/errata/RHSA-2026:22964 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:30848 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/security/cve/CVE-2026-43038 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:26535 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
access.redhat.com/errata/RHSA-2026:25121 0b0ca135-0b70-47e7-9f44-1890c2a1c46c access.redhat.com
CVE Program record CVE.ORG www.cve.org canonical
NVD vulnerability detail NVD nvd.nist.gov canonical, analysis

Additional Advisory Data

SourceTimeEvent
ADP2026-05-01T00:00:00.000ZReported to Red Hat.
ADP2026-05-01T00:00:00.000ZMade public.

Solutions

ADP: RHSA-2026:24343: Red Hat Enterprise Linux AppStream EUS (v. 10.0), Red Hat Enterprise Linux BaseOS EUS (v. 10.0), Red Hat Enterprise Linux CodeReady Linux Builder EUS (v. 10.0), Red Hat Enterprise Linux Real Time EUS (v. 10.0), Red Hat Enterprise Linux Real Time for NFV EUS (v. 10.0)

ADP: RHSA-2026:30129: Red Hat Enterprise Linux AppStream (v. 10), Red Hat Enterprise Linux BaseOS (v. 10), Red Hat Enterprise Linux CodeReady Linux Builder (v. 10), Red Hat Enterprise Linux Real Time (v. 10), Red Hat Enterprise Linux Real Time for NFV (v. 10)

ADP: RHSA-2026:22940: Red Hat Enterprise Linux AppStream E4S (v.9.2), Red Hat Enterprise Linux BaseOS E4S (v.9.2)

ADP: RHSA-2026:23237: Red Hat Enterprise Linux AppStream E4S (v.9.4), Red Hat Enterprise Linux BaseOS E4S (v.9.4), Red Hat Enterprise Linux Real Time E4S (v.9.4), Red Hat Enterprise Linux Real Time for NFV E4S (v.9.4)

ADP: RHSA-2026:23224: Red Hat CodeReady Linux Builder EUS (v.9.6), Red Hat Enterprise Linux AppStream EUS (v.9.6), Red Hat Enterprise Linux BaseOS EUS (v.9.6), Red Hat Enterprise Linux Real Time EUS (v.9.6), Red Hat Enterprise Linux Real Time for NFV EUS (v.9.6)

ADP: RHSA-2026:30848: Red Hat Enterprise Linux AppStream (v. 9), Red Hat Enterprise Linux BaseOS (v. 9), Red Hat Enterprise Linux CodeReady Linux Builder (v. 9), Red Hat Enterprise Linux Real Time (v. 9), Red Hat Enterprise Linux Real Time for NFV (v. 9)

ADP: RHSA-2026:25121: Red Hat Enterprise Linux BaseOS (v. 8), Red Hat Enterprise Linux CRB (v. 8)

ADP: RHSA-2026:26535: Red Hat Enterprise Linux BaseOS AUS (v.8.4), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.4)

ADP: RHSA-2026:25533: Red Hat Enterprise Linux BaseOS AUS (v.8.6), Red Hat Enterprise Linux BaseOS EUS EXTENSION (v.8.6)

ADP: RHSA-2026:22964: Red Hat Enterprise Linux BaseOS E4S (v.8.8), Red Hat Enterprise Linux BaseOS TUS (v.8.8)

ADP: RHSA-2026:25120: Red Hat Enterprise Linux NFV (v. 8), Red Hat Enterprise Linux RT (v. 8)

ADP: RHSA-2026:22900: Red Hat Enterprise Linux Real Time E4S (v.9.2), Red Hat Enterprise Linux Real Time for NFV E4S (v.9.2)

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