MediumCVE-2026-43094

    Linux Kernel: NULL Pointer Dereference (CVE-2026-43094)

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

    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: ixgbevf: add missing negotiate_features op to Hyper-V ops table Commit a7075f501bd3 ("ixgbevf: fix mailbox API compatibility by negotiating supported features") added the .negotiate_features callback to ixgbe_mac_operations and populated it in ixgbevf_mac_ops, but forgot to add it to ixgbevf_hv_mac_ops. This leaves the function pointer NULL on Hyper-V VMs.

    The available sources name no fixed version. Check the vendor guidance in the references below.

    Conflicting version data — version display is hidden until the data is resolved.

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    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 LTS, SUSE, Siemens ProductCERT, Ubuntu, BSI, CVE.org, EUVD

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 2.0

    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
    44.49 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
    2.0
    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

    In the Linux kernel, the following vulnerability has been resolved: ixgbevf: add missing negotiate_features op to Hyper-V ops table Commit a7075f501bd3 ("ixgbevf: fix mailbox API compatibility by negotiating supported features") added the .negotiate_features callback to ixgbe_mac_operations and populated it in ixgbevf_mac_ops, but forgot to add it to ixgbevf_hv_mac_ops. This leaves the function pointer NULL on Hyper-V VMs. During probe, ixgbevf_negotiate_api() calls ixgbevf_set_features(), which unconditionally dereferences hw->mac.ops.negotiate_features(). On Hyper-V this results in a NULL pointer dereference: BUG: kernel NULL pointer dereference, address: 0000000000000000 [...] Hardware name: Microsoft Corporation Virtual Machine/Virtual Machine [...] Workqueue: events work_for_cpu_fn RIP: 0010:0x0 [...] Call Trace: ixgbevf_negotiate_api+0x66/0x160 [ixgbevf] ixgbevf_sw_init+0xe4/0x1f0 [ixgbevf] ixgbevf_probe+0x20f/0x4a0 [ixgbevf] local_pci_probe+0x50/0xa0 work_for_cpu_fn+0x1a/0x30 [...] Add ixgbevf_hv_negotiate_features_vf() that returns -EOPNOTSUPP and wire it into ixgbevf_hv_mac_ops. The caller already handles -EOPNOTSUPP gracefully.

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

    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
    • 6.1.158 – < 6.1.175
    • 6.17.5 – < 6.18
    • 6.18 – < 6.18.24
    • 6.19 – < 6.19.14
    • 6.6.114 – < 6.6.136
    • 6.12.55 – < 6.12.83
    • 6.20 – < 7.0
    • 6.1.175
    • 6.18
    • 6.18.24
    • 6.19.14
    • 6.6.136
    • 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
    Linuxdebianlinux-6.1bullseye
    Linuxlinuxlinux_kernel6.18
    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 17 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/1455ff8809843e6e83f1f5b5c0bcc2224c99a3cb
      Referenceadded
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      https://git.kernel.org/stable/c/2270ebab53128fb73c4a70a292be09094074737f
      Referenceadded
      —
      https://git.kernel.org/stable/c/376d74ea03589914fbe2dedcbebf418396c04fd0
      Referenceadded
      —
      https://git.kernel.org/stable/c/4821d563cd7f251ae728be1a6d04af82a294a5b9
      Referenceadded
      —
      https://git.kernel.org/stable/c/4db7b61ec1d1b2b67c0881b62fc4f9583bc21484
      Referenceadded
      —
      https://git.kernel.org/stable/c/d8a747057a17ffc79e31df1abb11d05e1669d8e5
      Referenceremoved
      https://git.kernel.org/stable/c/1455ff8809843e6e83f1f5b5c0bcc2224c99a3cb
      —
      Referenceremoved
      https://git.kernel.org/stable/c/2270ebab53128fb73c4a70a292be09094074737f
      —
      Referenceremoved
      https://git.kernel.org/stable/c/376d74ea03589914fbe2dedcbebf418396c04fd0
      —
      Referenceremoved
      https://git.kernel.org/stable/c/4821d563cd7f251ae728be1a6d04af82a294a5b9
      —
      Referenceremoved
      https://git.kernel.org/stable/c/4db7b61ec1d1b2b67c0881b62fc4f9583bc21484
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d8a747057a17ffc79e31df1abb11d05e1669d8e5
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/1455ff8809843e6e83f1f5b5c0bcc2224c99a3cb Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/2270ebab53128fb73c4a70a292be09094074737f Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/4821d563cd7f251ae728be1a6d04af82a294a5b9 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/4db7b61ec1d1b2b67c0881b62fc4f9583bc21484 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/d8a747057a17ffc79e31df1abb11d05e1669d8e5 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/2026/43xxx/CVE-2026-43094.json">CVE-2026-43094</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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

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