MediumCVE-2026-23381

    Linux Kernel: NULL Pointer Dereference (CVE-2026-23381)

    Published Last modified Sources: Siemens ProductCERT, Debian, Debian LTS, Ubuntu, Red Hat, SUSE, BSI, CVE.org, EUVD, Msrc Update Guide

    What is affected, what to do

    A flaw was found in the Linux kernel's network bridging component. When Internet Protocol version 6 (IPv6) is explicitly disabled, a critical data structure for Neighbor Discovery is not properly initialized.

    Update Linux Kernel to version 5.10.253, Linux Kernel to version 5.15.203, Linux Kernel to version 6.1.167.

    Affected
    • Linux Kernel lt 4.15..5.10.253
    • Linux Kernel lt 5.11..5.15.203
    • Linux Kernel lt 5.16..6.1.167
    • Linux Kernel lt 6.2..6.6.130
    • Linux Kernel lt 6.7..6.12.77
    • Linux Kernel lt 6.13..6.18.17
    • Linux Kernel lt 6.19..6.19.7
    • Linux Kernel lt 6.20..7.0
    Fixed in
    • Linux Kernel 5.10.253
    • Linux Kernel 5.15.203
    • Linux Kernel 6.1.167
    • Linux Kernel 6.6.130
    • Linux Kernel 6.12.77
    • Linux Kernel 6.18.17
    • Linux Kernel 6.19.7
    • Linux Kernel 7.0

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

    Metrics

    5.5

    Priority

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

    Source: NVD, CVSS v3

    5.5

    CVSS v3

    Severity Medium on the scale from 0 to 10.

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

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 2.2

    Show all metrics
    Severity
    Medium
    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
    43.06 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
    5.5 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
    5.5
    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
    0.1 %
    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
    2.2
    Low — this CVE sits in the lower 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

    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
    Handle the vulnerability in regular vulnerability handling under Art. 21(2)(e) NIS2.
    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

    A flaw was found in the Linux kernel's network bridging component. When Internet Protocol version 6 (IPv6) is explicitly disabled, a critical data structure for Neighbor Discovery is not properly initialized. A remote attacker could exploit this by sending a specially crafted Internet Control Message Protocol version 6 (ICMPv6) Neighbor Discovery packet. This could lead to a kernel NULL pointer dereference, causing the system to crash and resulting in a Denial of Service (DoS).

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

    Affected products

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

    Affected products
    Affected versionsFixed in
    LinuxLinux
    • 6.7 – < 6.12.77
    • 4.15 – < 5.10.253
    • 6.2 – < 6.6.130
    • 5.11 – < 5.15.203
    • 6.20 – < 7.0
    • 6.19 – < 6.19.7
    • 6.13 – < 6.18.17
    • 5.16 – < 6.1.167
    • 6.12.77
    • 5.10.253
    • 6.6.130
    • 5.15.203
    • 7.0
    • 6.19.7
    • 6.18.17
    • 6.1.167
    SiemensSIMATIC S7
    • 1500 TM MFP V1.1.1 GNU/Linux subsystem
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxbullseye
    Linuxdebianlinuxtrixie
    Linuxdebianlinux-6.1bullseye
    Linuxlinuxlinux_kernel4.15
    Linuxlinuxlinux_kernel7.0
    Linuxlinuxlinux_kernel—

    References & sources

    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).

    1. Record modifiedLinux

      Show 24 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6
      Referenceadded
      —
      https://git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55
      Referenceadded
      —
      https://git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44
      Referenceadded
      —
      https://git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b
      Referenceadded
      —
      https://git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665
      Referenceadded
      —
      https://git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60
      Referenceadded
      —
      https://git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122
      Referenceadded
      —
      https://git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322
      Referenceremoved
      https://git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6
      —
      Referenceremoved
      https://git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55
      —
      Referenceremoved
      https://git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44
      —
      Referenceremoved
      https://git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b
      —
      Referenceremoved
      https://git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665
      —
      Referenceremoved
      https://git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60
      —
      Referenceremoved
      https://git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122
      —
      Referenceremoved
      https://git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/20ef5c25422f97dd09d751e5ae6c18406cdc78e6 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/33dec6f10777d5a8f71c0a200f690da5ae3c2e55 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/7a894eb5de246d79f13105c55a67381039a24d44 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/a12cdaa3375f0bd3c8f4e564be7c143529abfe5b Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/a5c56e65b685360dd3f2278aeff8c21061feb665 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/a9d712ccfeef737c0e700a4b5b98f310e07b6b60 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/aa73deb3b6b730ec280d45b3f423bfa9e17bc122 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/e5e890630533bdc15b26a34bb8e7ef539bdf1322 Types: Patch
      —

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

    2. Record modifiedSiemens ADP

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Affected value modified. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/23xxx/CVE-2026-23381.json">CVE-2026-23381</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-019113.html
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-082556.html
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-457936.html
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html
      Referenceremoved
      https://cert-portal.siemens.com/productcert/html/ssa-019113.html
      —
      Referenceremoved
      https://cert-portal.siemens.com/productcert/html/ssa-082556.html
      —

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

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