CriticalCVE-2026-64047

    Linux Kernel: Integer Underflow (Wrap or Wraparound) (CVE-2026-64047)

    Published Last modified Sources: SUSE, Ubuntu, 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: fix off-by-one in sg_chain entry count for wrapped sk_msg ring When an sk_msg scatterlist ring wraps (sg.end < sg.start), tls_push_record() chains the tail portion of the ring to the head using sg_chain(). An extra entry in the sg array is reserved for this: struct sk_msg_sg { [...] /* The extra two elements: * 1) used for chaining the front and sections when the list becomes * partitioned (e.g. end < start).

    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.

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

    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: SUSE, Ubuntu, 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
    85.10 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“.

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    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.

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    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-191

    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: fix off-by-one in sg_chain entry count for wrapped sk_msg ring When an sk_msg scatterlist ring wraps (sg.end < sg.start), tls_push_record() chains the tail portion of the ring to the head using sg_chain(). An extra entry in the sg array is reserved for this: struct sk_msg_sg { [...] /* The extra two elements: * 1) used for chaining the front and sections when the list becomes * partitioned (e.g. end < start). The crypto APIs require the * chaining; * 2) to chain tailer SG entries after the message. */ struct scatterlist data[MAX_MSG_FRAGS + 2]; The current code uses MAX_SKB_FRAGS + 1 as the ring size: sg_chain(&msg_pl->sg.data[msg_pl->sg.start], MAX_SKB_FRAGS - msg_pl->sg.start + 1, msg_pl->sg.data); This places the chain pointer at sg_chain(data[start], (MAX_SKB_FRAGS - msg_start + 1) .. = &data[start] + (MAX_SKB_FRAGS - msg_start + 1) - 1 = data[start + (MAX_SKB_FRAGS - start + 1) - 1] = data[MAX_SKB_FRAGS] instead of the true last entry. This is likely due to a "race" of the commit under Fixes landing close to commit 031097d9e079 ("bpf: sk_msg, zap ingress queue on psock down") Convert to ARRAY_SIZE and drop the data[start] / - start (as suggested by Sabrina).

    Source: suse_csaf, Ubuntu Security Notices, NVD (NIST), CVE.org (MITRE), cvelistv5, 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-191Integer Underflow (Wrap or Wraparound)

      Base

      The product subtracts one value from another, such that the result is less than the minimum allowable integer value, which produces a value that is not equal to the correct result.

      Entry at MITRE CWE-191

    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-191

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-191

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

    2. 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-2026-64047","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:35:54.546412Z"}

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

    3. Record modifiedLinux

      Show 24 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/131ef12057d92b77b636321b7849c69222405a97
      Referenceadded
      —
      https://git.kernel.org/stable/c/285943c6e7ca309bbea84b253745154241d9788a
      Referenceadded
      —
      https://git.kernel.org/stable/c/2fb0dc7e0099686c4e9d2732745d8a31b18c3628
      Referenceadded
      —
      https://git.kernel.org/stable/c/47110c3a9ac247b688657337f5981efcfcb240dc
      Referenceadded
      —
      https://git.kernel.org/stable/c/66339b71f105e6f83e0da3b9583d95077534fe1d
      Referenceadded
      —
      https://git.kernel.org/stable/c/73963a375885d5ccb7def39fd0b4f542e0f343dd
      Referenceadded
      —
      https://git.kernel.org/stable/c/84158c2997159df4a0d70cd9c46774512d32a522
      Referenceadded
      —
      https://git.kernel.org/stable/c/eca989eab4b2599dcb02f72140a7c08f08838520
      Referenceremoved
      https://git.kernel.org/stable/c/131ef12057d92b77b636321b7849c69222405a97
      —
      Referenceremoved
      https://git.kernel.org/stable/c/285943c6e7ca309bbea84b253745154241d9788a
      —
      Referenceremoved
      https://git.kernel.org/stable/c/2fb0dc7e0099686c4e9d2732745d8a31b18c3628
      —
      Referenceremoved
      https://git.kernel.org/stable/c/47110c3a9ac247b688657337f5981efcfcb240dc
      —
      Referenceremoved
      https://git.kernel.org/stable/c/66339b71f105e6f83e0da3b9583d95077534fe1d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/73963a375885d5ccb7def39fd0b4f542e0f343dd
      —
      Referenceremoved
      https://git.kernel.org/stable/c/84158c2997159df4a0d70cd9c46774512d32a522
      —
      Referenceremoved
      https://git.kernel.org/stable/c/eca989eab4b2599dcb02f72140a7c08f08838520
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/131ef12057d92b77b636321b7849c69222405a97 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/285943c6e7ca309bbea84b253745154241d9788a Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/2fb0dc7e0099686c4e9d2732745d8a31b18c3628 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/47110c3a9ac247b688657337f5981efcfcb240dc Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/66339b71f105e6f83e0da3b9583d95077534fe1d Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/73963a375885d5ccb7def39fd0b4f542e0f343dd Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/84158c2997159df4a0d70cd9c46774512d32a522 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/eca989eab4b2599dcb02f72140a7c08f08838520 Types: Patch
      —

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

    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)

      Weakness type: CWE-193

      Show 10 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-193
      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/131ef12057d92b77b636321b7849c69222405a97 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/285943c6e7ca309bbea84b253745154241d9788a Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/2fb0dc7e0099686c4e9d2732745d8a31b18c3628 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/47110c3a9ac247b688657337f5981efcfcb240dc Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/66339b71f105e6f83e0da3b9583d95077534fe1d Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/73963a375885d5ccb7def39fd0b4f542e0f343dd Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/84158c2997159df4a0d70cd9c46774512d32a522 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/eca989eab4b2599dcb02f72140a7c08f08838520 Types: Patch

      Source identifier: nvd@nist.gov

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