CriticalCVE-2026-64046

    Linux Kernel: Improper Input Validation (CVE-2026-64046)

    Published Last modified Sources: Ubuntu, SUSE, CVE.org, BSI

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: net: tls: prevent chain-after-chain in plain text SG Sashiko points out that if end = 0 (start != 0) the current code will create a chain link to content type right after the wrap link: This would create a chain where the wrap link points directly to another chain link. The scatterlist API sg_next iterator does not recursively resolve consecutive chain links. meaning this is illegal input to crypto.

    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

    9.8

    Priority

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

    Source: NVD, CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: Ubuntu, SUSE, CVE.org, BSI

    0.5 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 43.9

    Show all metrics
    Severity
    Critical
    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
    85.07 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
    9.8 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
    9.8
    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
    0.5 %
    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
    43.9
    High — this CVE ranks above the median of all CVEs scored today (rank ≥ 36%).
    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 · 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-20

    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: net: tls: prevent chain-after-chain in plain text SG Sashiko points out that if end = 0 (start != 0) the current code will create a chain link to content type right after the wrap link: This would create a chain where the wrap link points directly to another chain link. The scatterlist API sg_next iterator does not recursively resolve consecutive chain links. meaning this is illegal input to crypto. The wrapping link is unnecessary if end = 0. end is the entry after the last one used so end = 0 means there's nothing pushed after the wrap: end start i v v v [ ]...[ ][ d ][ d ][ d ][ d ][rsv for wrap] Skip the wrapping in this case. TLS 1.3 can use the "wrapping slot" for it's chaining if end = 0. This avoids the chain-after-chain. Move the wrap chaining before marking END and chaining off content type, that feels like more logical ordering to me, but should not matter from functional perspective.

    Source: Ubuntu Security Notices, suse_csaf, cvelistv5, NVD (NIST), CVE.org (MITRE), BSI WID Portal, BSI CSAF

    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
    • 6.19 – < 7.0.11
    • 5.5 – < 5.10.258
    • 5.4.14 – < 5.5
    • 6.13 – < 6.18.34
    • 5.11 – < 5.15.209
    • —
    • 6.7 – < 6.12.92
    • 6.2 – < 6.6.142
    • 6.1.175
    • 7.0.11
    • 5.10.258
    • 5.5
    • 6.18.34
    • 5.15.209
    • 7.1
    • 6.12.92
    • 6.6.142

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxubuntulinux-aws-fipsnoble
    Linuxubuntulinux-ibm-6.8jammy
    Linuxlinuxlinux_kernel5.5
    Linuxlinuxlinux_kernel7.1
    Linuxlinuxlinux_kernel—

    Weakness classes (CWE)

    • CWE-20Improper Input Validation

      Class

      The product receives input or data, but it does not validate or incorrectly validates that the input has the properties that are required to process the data safely and correctly.

      Entry at MITRE CWE-20

    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-20

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-20

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

    2. Record modifiedLinux

      Show 24 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/410351158dfef2d67fea6603680b3a6013c6ed9d
      Referenceadded
      —
      https://git.kernel.org/stable/c/49a5faaa471ddcd37b6893970c9916eb836e7c31
      Referenceadded
      —
      https://git.kernel.org/stable/c/91359966e247c0244c66d50bbb8e74aefa4321c3
      Referenceadded
      —
      https://git.kernel.org/stable/c/929b1548e63ac72e104c07d8ee8cbbeeba2fa89a
      Referenceadded
      —
      https://git.kernel.org/stable/c/acdc12b71c9aa4be5dcd2c8062753c6d2033e235
      Referenceadded
      —
      https://git.kernel.org/stable/c/af855f4c966afafef74faf8390c7b86568c0d46d
      Referenceadded
      —
      https://git.kernel.org/stable/c/b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36
      Referenceadded
      —
      https://git.kernel.org/stable/c/ff26a0e8377dec07e4a7230db7675bed1b9a6d03
      Referenceremoved
      https://git.kernel.org/stable/c/410351158dfef2d67fea6603680b3a6013c6ed9d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/49a5faaa471ddcd37b6893970c9916eb836e7c31
      —
      Referenceremoved
      https://git.kernel.org/stable/c/91359966e247c0244c66d50bbb8e74aefa4321c3
      —
      Referenceremoved
      https://git.kernel.org/stable/c/929b1548e63ac72e104c07d8ee8cbbeeba2fa89a
      —
      Referenceremoved
      https://git.kernel.org/stable/c/acdc12b71c9aa4be5dcd2c8062753c6d2033e235
      —
      Referenceremoved
      https://git.kernel.org/stable/c/af855f4c966afafef74faf8390c7b86568c0d46d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36
      —
      Referenceremoved
      https://git.kernel.org/stable/c/ff26a0e8377dec07e4a7230db7675bed1b9a6d03
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/410351158dfef2d67fea6603680b3a6013c6ed9d Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/49a5faaa471ddcd37b6893970c9916eb836e7c31 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/91359966e247c0244c66d50bbb8e74aefa4321c3 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/929b1548e63ac72e104c07d8ee8cbbeeba2fa89a Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/acdc12b71c9aa4be5dcd2c8062753c6d2033e235 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/af855f4c966afafef74faf8390c7b86568c0d46d Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/ff26a0e8377dec07e4a7230db7675bed1b9a6d03 Types: Patch
      —

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

    3. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: yes

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-64046","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:35:52.163580Z"}

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

    4. Initial analysis by NVDNVD

      Newly listed as affected:
      • Linux Kernel (5.16 – before 6.1.175; 5.11 – before 5.15.209; 6.7 – before 6.12.92; 6.13 – before 6.18.34; 6.19 – before 7.0.11; 6.2 – before 6.6.142; 5.4.14 – before 5.5; 5.5.1 – before 5.10.258; 5 individual versions)
      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      NVD-CWE-noinfo
      Product configurationadded
      —
      OR *cpe:2.3:o:linux:linux_kernel:5.5:-:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:5.5:rc7:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc2:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.16 up to (excluding) 6.1.175 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.11 up to (excluding) 5.15.209 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.7 up to (excluding) 6.12.92 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.13 up to (excluding) 6.18.34 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.0.11 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.2 up to (excluding) 6.6.142 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.4.14 up to (excluding) 5.5 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.5.1 up to (excluding) 5.10.258
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/410351158dfef2d67fea6603680b3a6013c6ed9d Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/49a5faaa471ddcd37b6893970c9916eb836e7c31 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/91359966e247c0244c66d50bbb8e74aefa4321c3 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/929b1548e63ac72e104c07d8ee8cbbeeba2fa89a Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/acdc12b71c9aa4be5dcd2c8062753c6d2033e235 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/af855f4c966afafef74faf8390c7b86568c0d46d Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/b9c015ef1a7bf1e8dc67f21c6381f36deb2c3a36 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/ff26a0e8377dec07e4a7230db7675bed1b9a6d03 Types: Patch

      Source identifier: nvd@nist.gov

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