CriticalCVE-2026-72351

    Linux Kernel: security vulnerability (CVE-2026-72351)

    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: gue: validate REMCSUM private option length GUE private flags can indicate that remote checksum offload metadata is present. The private flags field itself is accounted for by guehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even when GUE_PFLAG_REMCSUM is set.

    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 3.19..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..6.18.40
    • Linux Kernel lt 6.19..7.1.5
    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 6.18.40
    • Linux Kernel 7.1.5
    • Linux Kernel 7.2

    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: Vendor (CNA), CVSS v3

    9.8

    CVSS v3

    Severity Critical on the scale from 0 to 10.

    Source: SUSE, Ubuntu, CVE.org, BSI

    0.8 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 55.0

    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
    95.64 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
    0.8 %
    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
    55.0
    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

    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: gue: validate REMCSUM private option length GUE private flags can indicate that remote checksum offload metadata is present. The private flags field itself is accounted for by guehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even when GUE_PFLAG_REMCSUM is set. This lets a packet with only the private flags field pass validate_gue_flags(), after which gue_remcsum() and gue_gro_remcsum() read the missing REMCSUM start/offset fields from the following bytes. Account for GUE_PLEN_REMCSUM when GUE_PFLAG_REMCSUM is present so that malformed packets are rejected during option validation.

    Source: suse_csaf, Ubuntu Security Notices, cvelistv5, NVD (NIST), 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
    • 6.7 – < 6.12.97
    • 6.19 – < 7.1.5
    • 5.11 – < 5.15.212
    • 6.2 – < 6.6.145
    • 3.19 – < 5.10.261
    • —
    • 6.13 – < 6.18.40
    • 5.16 – < 6.1.178
    • 6.12.97
    • 7.1.5
    • 5.15.212
    • 6.6.145
    • 5.10.261
    • 7.2
    • 6.18.40
    • 6.1.178

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxubuntulinuxnoble
    Linuxubuntulinuxresolute
    Linuxubuntulinux-awsnoble
    Linuxubuntulinux-awsresolute
    Linuxubuntulinux-aws-7.0noble
    Linuxubuntulinux-aws-fipsnoble
    Linuxubuntulinux-azurenoble
    Linuxubuntulinux-azureresolute
    Linuxubuntulinux-azure-7.0noble
    Linuxubuntulinux-azure-fdenoble
    Linuxubuntulinux-azure-fderesolute
    Linuxubuntulinux-azure-fde-7.0noble
    Linuxubuntulinux-azure-fipsnoble
    Linuxubuntulinux-fipsnoble
    Linuxubuntulinux-gcpnoble
    Linuxubuntulinux-gcp-fipsnoble
    Linuxubuntulinux-gkenoble
    Linuxubuntulinux-gkeopnoble
    Linuxubuntulinux-hwe-7.0noble
    Linuxubuntulinux-ibmnoble
    Linuxubuntulinux-ibmresolute
    Linuxubuntulinux-lowlatencynoble
    Linuxubuntulinux-nvidiajammy
    Linuxubuntulinux-nvidia-7.0noble

    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 16 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/158b9995d3c87f3b93f5c22df54a12e12a3438b3
      Referenceadded
      —
      https://git.kernel.org/stable/c/2a99224c120823987e4d829726f4ecb33e03fc1e
      Referenceadded
      —
      https://git.kernel.org/stable/c/2c4de9988e9ddc760b750d6b6e701c35ff60ad14
      Referenceadded
      —
      https://git.kernel.org/stable/c/4a4a1d41c6e901e773bcf795f562a47fa71f692a
      Referenceadded
      —
      https://git.kernel.org/stable/c/61e78679c7c9ca685bff58e4b6348304dc60aafd
      Referenceadded
      —
      https://git.kernel.org/stable/c/7c6876ec1b227261b51803f784c7be1b2242a1a0
      Referenceadded
      —
      https://git.kernel.org/stable/c/d335dcc6f521571d57117b8deeebc940836e5450
      Referenceadded
      —
      https://git.kernel.org/stable/c/f618cbe9b24cd0202004d2db781d5f80ab77037f
      Referenceremoved
      https://git.kernel.org/stable/c/158b9995d3c87f3b93f5c22df54a12e12a3438b3
      —
      Referenceremoved
      https://git.kernel.org/stable/c/2a99224c120823987e4d829726f4ecb33e03fc1e
      —
      Referenceremoved
      https://git.kernel.org/stable/c/2c4de9988e9ddc760b750d6b6e701c35ff60ad14
      —
      Referenceremoved
      https://git.kernel.org/stable/c/4a4a1d41c6e901e773bcf795f562a47fa71f692a
      —
      Referenceremoved
      https://git.kernel.org/stable/c/61e78679c7c9ca685bff58e4b6348304dc60aafd
      —
      Referenceremoved
      https://git.kernel.org/stable/c/7c6876ec1b227261b51803f784c7be1b2242a1a0
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d335dcc6f521571d57117b8deeebc940836e5450
      —
      Referenceremoved
      https://git.kernel.org/stable/c/f618cbe9b24cd0202004d2db781d5f80ab77037f
      —

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

    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-2026-72351","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T18:47:48.615145Z"}

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

    3. Record modifiedLinux

      CVSS V3.1: AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

      Show 2 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      CVSSadded
      —
      AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
      Affected versions (publisher)changed
      Linux, Linux
      Linux, Linux

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

    4. 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: gue: validate REMCSUM private option length GUE private flags can indicate that remote checksum offload metadata is present. The private flags field itself is accounted for by guehdr_flags_len(), but guehdr_priv_flags_len() currently returns 0 even when GUE_PFLAG_REMCSUM is set. This lets a packet with only the private flags field pass validate_gue_flags(), after which gue_remcsum() and gue_gro_remcsum() read the missing REMCSUM start/offset fields from the following bytes. Account for GUE_PLEN_REMCSUM when GUE_PFLAG_REMCSUM is present so that malformed packets are rejected during option validation.
      Referenceadded
      —
      https://git.kernel.org/stable/c/158b9995d3c87f3b93f5c22df54a12e12a3438b3
      Referenceadded
      —
      https://git.kernel.org/stable/c/2a99224c120823987e4d829726f4ecb33e03fc1e
      Referenceadded
      —
      https://git.kernel.org/stable/c/2c4de9988e9ddc760b750d6b6e701c35ff60ad14
      Referenceadded
      —
      https://git.kernel.org/stable/c/4a4a1d41c6e901e773bcf795f562a47fa71f692a
      Referenceadded
      —
      https://git.kernel.org/stable/c/61e78679c7c9ca685bff58e4b6348304dc60aafd
      Referenceadded
      —
      https://git.kernel.org/stable/c/7c6876ec1b227261b51803f784c7be1b2242a1a0
      Referenceadded
      —
      https://git.kernel.org/stable/c/d335dcc6f521571d57117b8deeebc940836e5450
      Referenceadded
      —
      https://git.kernel.org/stable/c/f618cbe9b24cd0202004d2db781d5f80ab77037f

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

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