CriticalCVE-2026-43038

Linux Kernel: security vulnerability (CVE-2026-43038)

Published 01.05.2026Last modified 19.10.2026Sources: Debian LTS, Siemens ProductCERT, Ubuntu, Debian, SUSE, Red Hat, BSI, CVE.org, EUVD

What is affected, what to do

Update Linux Kernel to version 5.10.253, Linux Kernel to version 5.15.203, Linux Kernel to version 6.1.168.

Affected: Linux Kernel lt 3.13..5.10.253
Linux Kernel lt 5.11..5.15.203
Linux Kernel lt 5.16..6.1.168
Linux Kernel lt 6.2..6.6.134
Linux Kernel lt 6.7..6.12.81
Linux Kernel lt 6.13..6.18.22
Linux Kernel lt 6.19..6.19.12
Linux Kernel lt 6.20..7.0
Fixed in: Linux Kernel 5.10.253
Linux Kernel 5.15.203
Linux Kernel 6.1.168
Linux Kernel 6.6.134
Linux Kernel 6.12.81
Linux Kernel 6.18.22
Linux Kernel 6.19.12
Linux Kernel 7.0

Not sure whether and how you are affected? Ask a question about this vulnerability

Metrics

9.8

Priority

XIEM Effective CVSS: highest available CVSS rating from NVD and vendor data.

Source: NVD, CVSS v3

9.8

CVSS v3

Severity Critical on the scale from 0 to 10.

Source: Debian LTS, Siemens ProductCERT, Ubuntu, Debian, SUSE, Red Hat, BSI, CVE.org, EUVD

0.3 %

EPSS score

Low — model estimates < 1% exploitation likelihood.

Source: FIRST EPSS, percentile 17.0

Show all metrics

Severity: Critical
Priority (0–325) The priority score is a consolidated metric that condenses several individual signals into a single, action-guiding ranking: technical severity (CVSS), exploitation likelihood (EPSS), known-exploited status (KEV) and the context of the affected asset. The aim is to answer the only truly important question in vulnerability management: what first? Read in glossary: 68.26 Methodology
Exploit maturity An exploit is code or a technique that specifically uses a concrete vulnerability to force unintended behaviour — such as executing code or escalating privileges. It is the tool that turns a theoretical flaw into a practical attack. Read in glossary: no public PoC known
XIEM Effective CVSS XIEM® is the tiered managed-security operating model from NEOSEC and a registered trademark of NEOSEC GmbH. It extends classic SIEM — the central collection, normalisation and correlation of security-relevant events — with endpoint forensics, network visibility and deception technology, and consolidates them into three building tiers: Sentry, Orchestrate and Command. Read in glossary: 9.8 Methodology
CVSS v3 CVSS is the globally established, open standard for assessing the technical severity of a vulnerability on a scale from 0 to 10. It describes how easily a flaw can be exploited and what damage it can cause — but not how likely its actual exploitation is. CVSS and the complementary EPSS deliberately answer different questions. Read in glossary: 9.8
EPSS score The EPSS score is the absolute model output for an individual vulnerability: the estimated probability of real-world exploitation within the next 30 days, expressed as a value between 0 and 1 (i.e. 0 % to 100 %). A score of 0.42 means „the model estimates a 42 % chance of real-world exploitation within 30 days“. Read in glossary: 0.3 %; Low — model estimates < 1% exploitation likelihood.
EPSS percentile The EPSS percentile is the relative position of a vulnerability within all EPSS-scored CVEs, expressed as a value between 0 and 1. A percentile of 0.90 means „this CVE has a higher EPSS score than 90 % of all other scored CVEs“. Unlike the EPSS score, it is not a probability — but a positioning within a ranking. Read in glossary: 17.0; Elevated — this CVE ranks above at least 10% of all CVEs scored today.
KEV status The KEV catalogue is a list maintained by the US authority CISA of vulnerabilities for which active exploitation in the wild has been confirmed. It answers not the question „how severe?“ but „is it already being attacked?“ — thereby sharply prioritising patching. Read in glossary: —
Published: 01.05.2026

Detection rules

No NEOSEC detection rule is available for this vulnerability yet.

Classification under NIS2 and CRA

Rule-based classification from exploitation status and severity. It does not replace a case-by-case assessment.

NIS2 NIS2 is EU Directive (EU) 2022/2555 to raise the level of cybersecurity across the Union. It substantially broadens obligations compared with the first NIS directive: more sectors, mandatory risk management, staged reporting duties and personal accountability of senior management. Read in glossary: High technical severity: assess and remediate the vulnerability in vulnerability handling under Art. 21(2)(e) NIS2 and document the decision.
CRA The CRA is EU Regulation (EU) 2024/2847 setting horizontal cybersecurity requirements for „products with digital elements“ — from industrial controllers and software to connected consumer devices. For the first time manufacturers must ensure security across the entire product lifecycle, handle vulnerabilities and provide security updates. Read in glossary: From 11.12.2027, Annex I Part II CRA requires manufacturers of affected products with digital elements to handle vulnerabilities without delay and provide security updates.
ISO/IEC 27001 ISO/IEC 27001 is the internationally leading standard for an information security management system (ISMS). It describes a risk-based, process-oriented framework to systematically plan, implement, review and improve information security. Read in glossary: Control A.8.8, management of technical vulnerabilities: assess relevance to your systems, plan remediation and keep evidence.

Description

In 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.

Source: Debian LTS Advisories, siemens_advisory, Ubuntu Security Notices, Debian Security Advisories, suse_csaf, redhat_csaf, BSI WID Portal, BSI CSAF, NVD (NIST), ENISA EUVD, CVE.org (MITRE), cvelistv5

Affected products

The following versions are affected. Older releases of the same product line are also vulnerable unless stated otherwise.

Affected products
		Affected versions	Fixed in
Linux	Linux	`3.13 – < 5.10.253` `6.19 – < 6.19.12` `5.16 – < 6.1.168` `6.13 – < 6.18.22` `5.11 – < 5.15.203` `6.20 – < 7.0` `6.7 – < 6.12.81` `6.2 – < 6.6.134`	`5.10.253` `6.19.12` `6.1.168` `6.18.22` `5.15.203` `7.0` `6.12.81` `6.6.134`
IBM	DataPower Gateway	`< 11.0.0.3` `< 10.6.0.11` `< 10.5.0.23`	`11.0.0.3` `10.6.0.11` `10.5.0.23`
Microsoft	Azure Linux	`azl3`	—

Vendors and products

Affected operating systems

Affected operating systems

Linux	debian	linux	`bookworm`
Linux	debian	linux	`bullseye`
Linux	debian	linux-6.1	`bullseye`
Linux	linux	linux_kernel	`3.13`
Linux	linux	linux_kernel	`7.0`
Linux	linux	linux_kernel	—

References & sources

git.kernel.orgstable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8euvd, Patch
git.kernel.orgstable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7euvd, Patch
git.kernel.orgstable/c/a4437faf135da293d16fcc4cc607316742bd0ebbeuvd, Patch
git.kernel.orgstable/c/3d5127d998de617b130aae96b138dba22ac6a8a7euvd, Patch
git.kernel.orgstable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4eeuvd, Patch
git.kernel.orgstable/c/a2edbb6393972a02114b6003953a5cef3104fadaeuvd, Patch
git.kernel.orgstable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cfeuvd, Patch
git.kernel.orgstable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5euvd, Patch
access.redhat.comsecurity/cve/CVE-2026-43038Vulnerability database, x_refsource_REDHAT
bugzilla.redhat.comRHBZ#2464397Issue tracking, x_refsource_REDHAT
security.access.redhat.comdata/csaf/v2/vex/2026/cve-2026-43038.jsonx_sadp-csaf-vex
access.redhat.comerrata/RHSA-2026:24343Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:30129Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:22940Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:23237Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:23224Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:30848Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:55618Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:25121Vendor advisory, x_refsource_REDHAT
access.redhat.comerrata/RHSA-2026:55762Vendor advisory, x_refsource_REDHAT

Changes to this CVE

Who changed this CVE and when: NVD (analysis, affected products, CVSS), the CVE publisher (CNA) and additional providers such as CISA (ADP).

19.10.2026Record modifiedCISA ADP
Weakness type: CWE-787
Show the original change
Individual changes of this event as published by NVD
Type Action Before After
Weakness type (CWE) added
—
CWE-787
Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

Individual changes of this event as published by NVD
Type	Action	Before	After
Weakness type (CWE)	added	—	CWE-787

16.10.2026Record modifiedCISA ADP

CISA assessment (SSVC): exploitation: none known, automatable: yes

Show the original change

Individual changes of this event as published by NVD
Type	Action	Before	After
SSVC assessment	added	—	{"id":"CVE-2026-43038","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:13:51.083279Z"}

Source identifier: 134c704f-9b21-4f2e-91b3-4a467353bcc0

15.10.2026Record modifiedLinux

New references:

and 4 more references

Show 24 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7
Reference	added	—	https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf
Reference	added	—	https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7
Reference	added	—	https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5
Reference	added	—	https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada
Reference	added	—	https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb
Reference	added	—	https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8
Reference	added	—	https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e
Reference	removed	https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7	—
Reference	removed	https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf	—
Reference	removed	https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7	—
Reference	removed	https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5	—
Reference	removed	https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada	—
Reference	removed	https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb	—
Reference	removed	https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8	—
Reference	removed	https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e	—
Reference type	removed	https://git.kernel.org/stable/c/0452b6526b2f54b2413b9cb4ff1ea2ac542c99c7 Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/1ceeebd5bd6d855b17a5df625109bfe29129d7cf Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/3d5127d998de617b130aae96b138dba22ac6a8a7 Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/86ab3e55673a7a49a841838776f1ab18d23a67b5 Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/a2edbb6393972a02114b6003953a5cef3104fada Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/a4437faf135da293d16fcc4cc607316742bd0ebb Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/c438ba010171b70bad22fc18b1d5bdc3627476e8 Types: Patch	—
Reference type	removed	https://git.kernel.org/stable/c/e41953e7d118e2702bcb217879c173d9d1d3cd4e Types: Patch	—

Source identifier: 416baaa9-dc9f-4396-8d5f-8c081fb06d67

15.10.2026Record modifiedRed Hat ADP

New references:

and 8 more references

Show 44 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:22900
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:22940
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:22964
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:23224
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:23237
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:24343
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:25120
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:25121
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:25533
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:26535
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:30129
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:30848
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55618
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55761
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55762
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55763
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55837
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:56224
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:56225
Reference	added	—	https://access.redhat.com/security/cve/CVE-2026-43038
Reference	added	—	https://bugzilla.redhat.com/show_bug.cgi?id=2464397
Reference	added	—	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43038.json
Reference	removed	https://access.redhat.com/errata/RHSA-2026:22900	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:22940	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:22964	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:23224	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:23237	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:24343	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:25120	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:25121	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:25533	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:26535	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:30129	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:30848	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:55618	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:55761	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:55762	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:55763	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:55837	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:56224	—
Reference	removed	https://access.redhat.com/errata/RHSA-2026:56225	—
Reference	removed	https://access.redhat.com/security/cve/CVE-2026-43038	—
Reference	removed	https://bugzilla.redhat.com/show_bug.cgi?id=2464397	—
Reference	removed	https://security.access.redhat.com/data/csaf/v2/vex/2026/cve-2026-43038.json	—

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

15.10.2026Record modifiedSiemens ADP

New references:

Show 6 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Affected versions (publisher)	added	—	Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/43xxx/CVE-2026-43038.json">CVE-2026-43038</a>
Reference	added	—	https://cert-portal.siemens.com/productcert/html/ssa-019113.html
Reference	added	—	https://cert-portal.siemens.com/productcert/html/ssa-082556.html
Reference	added	—	https://cert-portal.siemens.com/productcert/html/ssa-457936.html
Reference	removed	https://cert-portal.siemens.com/productcert/html/ssa-019113.html	—
Reference	removed	https://cert-portal.siemens.com/productcert/html/ssa-082556.html	—

Source identifier: 0b142b55-0307-4c5a-b3c9-f314f3fb7c5e

Show 3 older changes

20.08.2026Record modifiedRed Hat ADP

New references:

https://access.redhat.com/errata/RHSA-2026:55761

Show 2 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55761
Affected versions (publisher)	changed	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support (+22)	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support (+23)

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

19.08.2026Record modifiedRed Hat ADP

New references:

Show 3 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:56224
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:56225
Affected versions (publisher)	changed	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support (+20)	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support (+22)

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

18.08.2026Record modifiedRed Hat ADP

New references:

Show 5 original changes

Individual changes of this event as published by NVD
Type	Action	Before	After
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55618
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55762
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55763
Reference	added	—	https://access.redhat.com/errata/RHSA-2026:55837
Affected versions (publisher)	changed	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support, Red Hat Enterprise Linux 8 (+16)	Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10, Red Hat Enterprise Linux 10.0 Extended Update Support (+20)

Source identifier: 0b0ca135-0b70-47e7-9f44-1890c2a1c46c

Linked advisories

Fwd: @RISK®: The Consensus Security Vulnerability Alert: Vol. 26, Num. 20SANS @RISK21.05.2026
Fwd: @RISK®: The Consensus Security Vulnerability Alert: Vol. 26, Num. 19SANS @RISK14.05.2026

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<a href="https://intel.neosec.eu/en/cve/CVE-2026-43038"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-43038.svg?lang=en" alt="CVE-2026-43038 – NEOSEC Intel" height="20"></a>