MediumCVE-2026-23442

    Linux Kernel: NULL Pointer Dereference (CVE-2026-23442)

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

    What is affected, what to do

    A flaw was found in the Linux kernel. Missing null pointer checks in the IPv6 Segment Routing (SRv6) implementation, specifically within the `seg6_hmac_validate_skb()` and `ipv6_srh_rcv()` functions, can occur when an IPv6 device lacks proper configuration.

    Update Linux Kernel to version 5.10.258, Linux Kernel to version 5.15.209, Linux Kernel to version 6.1.175.

    Affected
    • Linux Kernel lt 4.10..5.10.258
    • Linux Kernel lt 5.11..5.15.209
    • Linux Kernel lt 5.16..6.1.175
    • Linux Kernel lt 6.2..6.6.136
    • Linux Kernel lt 6.7..6.12.83
    • Linux Kernel lt 6.13..6.18.25
    • Linux Kernel lt 6.19..6.19.10
    • Linux Kernel lt 6.20..7.0
    Fixed in
    • Linux Kernel 5.10.258
    • Linux Kernel 5.15.209
    • Linux Kernel 6.1.175
    • Linux Kernel 6.6.136
    • Linux Kernel 6.12.83
    • Linux Kernel 6.18.25
    • Linux Kernel 6.19.10
    • 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: Debian, Debian LTS, Siemens ProductCERT, SUSE, Ubuntu, Red Hat, BSI, CVE.org, Msrc Update Guide, EUVD

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 2.5

    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
    43.38 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
    2.5
    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. Missing null pointer checks in the IPv6 Segment Routing (SRv6) implementation, specifically within the `seg6_hmac_validate_skb()` and `ipv6_srh_rcv()` functions, can occur when an IPv6 device lacks proper configuration. This oversight may allow an attacker to trigger a null pointer dereference, potentially leading to a system crash and a Denial of Service (DoS).

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

    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
    • 5.16 – < 6.1.175
    • 6.2 – < 6.6.136
    • 6.13 – < 6.18.25
    • 4.10 – < 5.10.258
    • 5.11 – < 5.15.209
    • 6.19 – < 6.19.10
    • 6.7 – < 6.12.83
    • 6.20 – < 7.0
    • 6.1.175
    • 6.6.136
    • 6.18.25
    • 5.10.258
    • 5.15.209
    • 6.19.10
    • 6.12.83
    • 7.0
    MicrosoftAzure Linux
    • azl3
    • —
    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_kernel4.10
    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 19 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/0348fa0ada37cef7c6b5ab2a428bb2c6aee784e4
      Referenceadded
      —
      https://git.kernel.org/stable/c/06413793526251870e20402c39930804f14d59c0
      Referenceadded
      —
      https://git.kernel.org/stable/c/50352fc103928e10e8729abc79a0d05abef26c4d
      Referenceadded
      —
      https://git.kernel.org/stable/c/83d705d35e583cb1b1eacf196dfe7b77d442018e
      Referenceadded
      —
      https://git.kernel.org/stable/c/a25853c9feea7bbf31d157ff6e004d2d3b4f7f13
      Referenceadded
      —
      https://git.kernel.org/stable/c/bc9843c39f9932a8b36efd1d362ea00bb88e4e78
      Referenceadded
      —
      https://git.kernel.org/stable/c/c5cedee5d97382176573bbe21e1724e737a5eb64
      Referenceadded
      —
      https://git.kernel.org/stable/c/d1bd8b9edc6752d10f84d28ff64f842401ce336d
      Referenceremoved
      https://git.kernel.org/stable/c/0348fa0ada37cef7c6b5ab2a428bb2c6aee784e4
      —
      Referenceremoved
      https://git.kernel.org/stable/c/06413793526251870e20402c39930804f14d59c0
      —
      Referenceremoved
      https://git.kernel.org/stable/c/50352fc103928e10e8729abc79a0d05abef26c4d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/83d705d35e583cb1b1eacf196dfe7b77d442018e
      —
      Referenceremoved
      https://git.kernel.org/stable/c/a25853c9feea7bbf31d157ff6e004d2d3b4f7f13
      —
      Referenceremoved
      https://git.kernel.org/stable/c/bc9843c39f9932a8b36efd1d362ea00bb88e4e78
      —
      Referenceremoved
      https://git.kernel.org/stable/c/c5cedee5d97382176573bbe21e1724e737a5eb64
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d1bd8b9edc6752d10f84d28ff64f842401ce336d
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/06413793526251870e20402c39930804f14d59c0 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/a25853c9feea7bbf31d157ff6e004d2d3b4f7f13 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/bc9843c39f9932a8b36efd1d362ea00bb88e4e78 Types: Patch
      —

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

    2. Record modifiedSiemens ADP

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/23xxx/CVE-2026-23442.json">CVE-2026-23442</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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

    One NVD translation into another language is hidden.

    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2026-23442
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-23442"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-23442.svg?lang=en" alt="CVE-2026-23442 – NEOSEC Intel" height="20"></a>