MediumCVE-2026-43309

    Linux Kernel: security vulnerability (CVE-2026-43309)

    Published Last modified Sources: SUSE, BSI, CVE.org, Msrc Update Guide, EUVD

    What is affected, what to do

    Update Linux Kernel to version 4.15, Linux Kernel to version 4.20, Linux Kernel to version 5.5.

    Affected
    • Linux Kernel lt 4.14.292..4.15
    • Linux Kernel lt 4.19.257..4.20
    • Linux Kernel lt 5.4.212..5.5
    • Linux Kernel lt 5.10.140..5.11
    • Linux Kernel lt 5.15.64..5.16
    • Linux Kernel lt 5.19.6..5.20
    • Linux Kernel lt 6.0..6.12.114
    • Linux Kernel lt 6.13..6.18.16
    • Linux Kernel lt 6.19..6.19.6
    • Linux Kernel lt 6.20..7.0
    Fixed in
    • Linux Kernel 4.15
    • Linux Kernel 4.20
    • Linux Kernel 5.5
    • Linux Kernel 5.11
    • Linux Kernel 5.16
    • Linux Kernel 5.20
    • Linux Kernel 6.12.114
    • Linux Kernel 6.18.16
    • Linux Kernel 6.19.6
    • 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: SUSE, BSI, CVE.org, Msrc Update Guide, 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
    44.78 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:

    md raid: fix hang when stopping arrays with metadata through dm-raid

    When using device-mapper's dm-raid target, stopping a RAID array can cause the system to hang under specific conditions.

    This occurs when:

    • A dm-raid managed device tree is suspended from top to bottom (the top-level RAID device is suspended first, followed by its underlying metadata and data devices)

    • The top-level RAID device is then removed

    Removing the top-level device triggers a hang in the following sequence: the dm-raid destructor calls md_stop(), which tries to flush the write-intent bitmap by writing to the metadata sub-devices. However, these devices are already suspended, making them unable to complete the write-intent operations and causing an indefinite block.

    Fix:

    • Prevent bitmap flushing when md_stop() is called from dm-raid destructor context and avoid a quiescing/unquescing cycle which could also cause I/O

    • Still allow write-intent bitmap flushing when called from dm-raid suspend context

    This ensures that RAID array teardown can complete successfully even when the underlying devices are in a suspended state.

    This second patch uses md_is_rdwr() to distinguish between suspend and destructor paths as elaborated on above.

    Source: suse_csaf, BSI WID Portal, BSI CSAF, NVD (NIST), Microsoft Security Update Guide, CVE.org (MITRE), cvelistv5, 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
    • 6.19 – < 6.19.6
    • 5.19.6 – < 5.20
    • 4.14.292 – < 4.15
    • 6.0 – < 6.12.114
    • 6.20 – < 7.0
    • 4.19.257 – < 4.20
    • 5.15.64 – < 5.16
    • 6.13 – < 6.18.16
    • 5.10.140 – < 5.11
    • 5.4.212 – < 5.5
    • 6.19.6
    • 5.20
    • 4.15
    • 6.12.114
    • 7.0
    • 4.20
    • 5.16
    • 6.18.16
    • 5.11
    • 5.5
    MicrosoftAzure Linux
    • azl3
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxlinuxlinux_kernel6.0
    Linuxlinuxlinux_kernel—

    References & sources

    • git.kernel.orgstable/c/24783dd06de870d646c25207bae186f78195f912euvd, Patch
    • git.kernel.orgstable/c/338378dfffbdbb8d37a18f0a0c0358812671f91eeuvd, Patch
    • git.kernel.orgstable/c/cefcb9297fbdb6d94b61787b4f8d84f55b741470euvd, Patch
    • git.kernel.orgstable/c/63054027d95200b04f3cf624faa7817e0555d56a

    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 11 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/2026/43xxx/CVE-2026-43309.json">CVE-2026-43309</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/24783dd06de870d646c25207bae186f78195f912
      Referenceadded
      —
      https://git.kernel.org/stable/c/338378dfffbdbb8d37a18f0a0c0358812671f91e
      Referenceadded
      —
      https://git.kernel.org/stable/c/63054027d95200b04f3cf624faa7817e0555d56a
      Referenceadded
      —
      https://git.kernel.org/stable/c/cefcb9297fbdb6d94b61787b4f8d84f55b741470
      Referenceremoved
      https://git.kernel.org/stable/c/24783dd06de870d646c25207bae186f78195f912
      —
      Referenceremoved
      https://git.kernel.org/stable/c/338378dfffbdbb8d37a18f0a0c0358812671f91e
      —
      Referenceremoved
      https://git.kernel.org/stable/c/cefcb9297fbdb6d94b61787b4f8d84f55b741470
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/24783dd06de870d646c25207bae186f78195f912 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/338378dfffbdbb8d37a18f0a0c0358812671f91e Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/cefcb9297fbdb6d94b61787b4f8d84f55b741470 Types: Patch
      —

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

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