HighCVE-2026-64413

    Linux Kernel: Use of Uninitialized Variable (CVE-2026-64413)

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

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: zero chainstack array sashiko reports: looking at ebtables table translation, could a sparse cpu_possible_mask lead to an uninitialized pointer free? If cpu_possible_mask is sparse (for example, CPU 0 and CPU 2 are possible, but CPU 1 is not), the allocation loop skips CPU 1. If vmalloc_node() fails at CPU 2, the cleanup loop will blindly decrement and call vfree() on newinfo->chainstack[1].

    Update Linux Kernel to version 5.10.261, Linux Kernel to version 5.15.212, Linux Kernel to version 6.1.178.

    Affected
    • Linux Kernel lt 2.6.12..5.10.261
    • Linux Kernel lt 5.11..5.15.212
    • Linux Kernel lt 5.16..6.1.178
    • Linux Kernel lt 6.2..6.6.145
    • Linux Kernel lt 6.7..6.12.97
    • Linux Kernel lt 6.13..6.18.39
    • Linux Kernel lt 6.19..7.1.4
    Fixed in
    • Linux Kernel 5.10.261
    • Linux Kernel 5.15.212
    • Linux Kernel 6.1.178
    • Linux Kernel 6.6.145
    • Linux Kernel 6.12.97
    • Linux Kernel 6.18.39
    • Linux Kernel 7.1.4
    • Linux Kernel 7.2

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

    Metrics

    7.0

    Priority

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

    Source: Vendor (CNA), CVSS v3

    7.0

    CVSS v3

    Severity High on the scale from 0 to 10.

    Source: Siemens ProductCERT, Ubuntu, Debian LTS, Debian, BSI, CVE.org, Msrc Update Guide

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 2.5

    Show all metrics
    Severity
    High
    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
    56.02 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
    7.0 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
    7.0
    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
    CISA assessment (SSVC)
    Exploitation: none known · not automatable · Technical impact: total
    Source: CISA Vulnrichment, as of 16 October 2026
    CWE

    CWE is a catalogue of typical weakness types in software and hardware — such as flawed input validation, unsafe memory handling or poor authentication. Where a CVE names a concrete vulnerability in a concrete product, a CWE describes the underlying class of defect.

    Read in glossary
    CWE-457

    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: netfilter: ebtables: zero chainstack array sashiko reports: looking at ebtables table translation, could a sparse cpu_possible_mask lead to an uninitialized pointer free? If cpu_possible_mask is sparse (for example, CPU 0 and CPU 2 are possible, but CPU 1 is not), the allocation loop skips CPU 1. If vmalloc_node() fails at CPU 2, the cleanup loop will blindly decrement and call vfree() on newinfo->chainstack[1]. Not a real-world bug, such allocation isn't expected to fail in the first place.

    Source: siemens_advisory, Ubuntu Security Notices, Debian LTS Advisories, Debian Security Advisories, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), 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 – < 6.12.97
    • 5.11 – < 5.15.212
    • 2.6.12 – < 5.10.261
    • 6.19 – < 7.1.4
    • 6.2 – < 6.6.145
    • —
    • 6.13 – < 6.18.39
    • 5.16 – < 6.1.178
    • 6.12.97
    • 5.15.212
    • 5.10.261
    • 7.1.4
    • 6.6.145
    • 7.2
    • 6.18.39
    • 6.1.178

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxbullseye
    Linuxdebianlinuxtrixie
    Linuxubuntulinuxnoble
    Linuxdebianlinux-6.1bullseye
    Linuxdebianlinux-6.12bookworm
    Linuxubuntulinux-awsnoble
    Linuxubuntulinux-aws-fipsnoble
    Linuxubuntulinux-azurenoble
    Linuxubuntulinux-azure-fdenoble
    Linuxubuntulinux-azure-fipsnoble
    Linuxubuntulinux-fipsnoble
    Linuxubuntulinux-gcpnoble
    Linuxubuntulinux-gcp-fipsnoble
    Linuxubuntulinux-gkenoble
    Linuxubuntulinux-gkeopnoble
    Linuxubuntulinux-ibmnoble
    Linuxubuntulinux-lowlatencynoble
    Linuxubuntulinux-nvidiajammy
    Linuxubuntulinux-nvidia-tegrajammy
    Linuxubuntulinux-nvidia-tegra-5.15focal
    Linuxubuntulinux-nvidia-tegra-igxjammy
    Linuxubuntulinux-oraclenoble
    Linuxubuntulinux-realtimenoble

    Weakness classes (CWE)

    • CWE-457Use of Uninitialized Variable

      Variant

      The code uses a variable that has not been initialized, leading to unpredictable or unintended results.

      Entry at MITRE CWE-457

    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 modifiedCISA ADP

      Weakness type: CWE-457

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-457

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

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-64413","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:40:24.345597Z"}

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

    3. Record modifiedSiemens ADP

      Show 2 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/2026/64xxx/CVE-2026-64413.json">CVE-2026-64413</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-457936.html

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

    4. Record modifiedLinux

      Show 24 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/29bf41a9b59aff9f6197df58641a00037d567ca8
      Referenceadded
      —
      https://git.kernel.org/stable/c/2ade612967e2cdfb9290ebcb773f302c82f311fa
      Referenceadded
      —
      https://git.kernel.org/stable/c/42bef500d07b5769d916e9122a3e3fa3fd2245ef
      Referenceadded
      —
      https://git.kernel.org/stable/c/5ee856e4208acafaaaf7b84824d39b78c21345d6
      Referenceadded
      —
      https://git.kernel.org/stable/c/9e6c5169db423e51dcc66a73fd15409c0d38e088
      Referenceadded
      —
      https://git.kernel.org/stable/c/9f74d28e903fa4fdf82f870d0aeadddc8196e41c
      Referenceadded
      —
      https://git.kernel.org/stable/c/cbfe53599eebffd188938ab6774cc41794f6f9d5
      Referenceadded
      —
      https://git.kernel.org/stable/c/fc7f105451044501a50cfd530cfa3b472c54acbc
      Referenceremoved
      https://git.kernel.org/stable/c/29bf41a9b59aff9f6197df58641a00037d567ca8
      —
      Referenceremoved
      https://git.kernel.org/stable/c/2ade612967e2cdfb9290ebcb773f302c82f311fa
      —
      Referenceremoved
      https://git.kernel.org/stable/c/42bef500d07b5769d916e9122a3e3fa3fd2245ef
      —
      Referenceremoved
      https://git.kernel.org/stable/c/5ee856e4208acafaaaf7b84824d39b78c21345d6
      —
      Referenceremoved
      https://git.kernel.org/stable/c/9e6c5169db423e51dcc66a73fd15409c0d38e088
      —
      Referenceremoved
      https://git.kernel.org/stable/c/9f74d28e903fa4fdf82f870d0aeadddc8196e41c
      —
      Referenceremoved
      https://git.kernel.org/stable/c/cbfe53599eebffd188938ab6774cc41794f6f9d5
      —
      Referenceremoved
      https://git.kernel.org/stable/c/fc7f105451044501a50cfd530cfa3b472c54acbc
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/29bf41a9b59aff9f6197df58641a00037d567ca8 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/2ade612967e2cdfb9290ebcb773f302c82f311fa Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/42bef500d07b5769d916e9122a3e3fa3fd2245ef Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/5ee856e4208acafaaaf7b84824d39b78c21345d6 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/9e6c5169db423e51dcc66a73fd15409c0d38e088 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/9f74d28e903fa4fdf82f870d0aeadddc8196e41c Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/cbfe53599eebffd188938ab6774cc41794f6f9d5 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/fc7f105451044501a50cfd530cfa3b472c54acbc Types: Patch
      —

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

    5. 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/2026/64xxx/CVE-2026-64413.json">CVE-2026-64413</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-019113.html

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

    Show 2 older changes

    1. Record modifiedLinux

      1 individual change: Affected versions (publisher)

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)changed
      Linux, Linux
      Linux, Linux

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

    2. ReceivedLinux

      Description added or changed

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Affected versions (publisher)added
      —
      Linux, Linux
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: netfilter: ebtables: zero chainstack array sashiko reports: looking at ebtables table translation, could a sparse cpu_possible_mask lead to an uninitialized pointer free? If cpu_possible_mask is sparse (for example, CPU 0 and CPU 2 are possible, but CPU 1 is not), the allocation loop skips CPU 1. If vmalloc_node() fails at CPU 2, the cleanup loop will blindly decrement and call vfree() on newinfo->chainstack[1]. Not a real-world bug, such allocation isn't expected to fail in the first place.
      Referenceadded
      —
      https://git.kernel.org/stable/c/29bf41a9b59aff9f6197df58641a00037d567ca8
      Referenceadded
      —
      https://git.kernel.org/stable/c/2ade612967e2cdfb9290ebcb773f302c82f311fa
      Referenceadded
      —
      https://git.kernel.org/stable/c/42bef500d07b5769d916e9122a3e3fa3fd2245ef
      Referenceadded
      —
      https://git.kernel.org/stable/c/5ee856e4208acafaaaf7b84824d39b78c21345d6
      Referenceadded
      —
      https://git.kernel.org/stable/c/9e6c5169db423e51dcc66a73fd15409c0d38e088
      Referenceadded
      —
      https://git.kernel.org/stable/c/9f74d28e903fa4fdf82f870d0aeadddc8196e41c
      Referenceadded
      —
      https://git.kernel.org/stable/c/cbfe53599eebffd188938ab6774cc41794f6f9d5
      Referenceadded
      —
      https://git.kernel.org/stable/c/fc7f105451044501a50cfd530cfa3b472c54acbc

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

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