MediumCVE-2026-80807

    Linux Kernel: security vulnerability (CVE-2026-80807)

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

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: nilfs2: reject invalid block index in GC ioctl Syzbot reported list corruption caused by a double list_add_tail() call on bh->b_assoc_buffers within nilfs_lookup_dirty_data_buffers(). Analysis revealed that the root cause was the insertion of a page/folio with a page index of ULONG_MAX into the page cache via the GC ioctl. filemap_get_folios_tag(), called by nilfs_lookup_dirty_data_buffers(), repeatedly detects a dirty folio with a page index of ULONG_MAX due to index wrap-around, leading to duplicate processing of dirty buffers.

    Update Linux Kernel to version 5.10.269, Linux Kernel to version 5.15.220, Linux Kernel to version 6.1.187.

    Affected
    • Linux Kernel lt 2.6.30..5.10.269
    • Linux Kernel lt 5.11..5.15.220
    • Linux Kernel lt 5.16..6.1.187
    • Linux Kernel lt 6.2..6.6.156
    • Linux Kernel lt 6.7..6.12.108
    • Linux Kernel lt 6.13..6.18.47
    • Linux Kernel lt 6.19..7.1.11
    • Linux Kernel lt 7.2..7.2.1
    Fixed in
    • Linux Kernel 5.10.269
    • Linux Kernel 5.15.220
    • Linux Kernel 6.1.187
    • Linux Kernel 6.6.156
    • Linux Kernel 6.12.108
    • Linux Kernel 6.18.47
    • Linux Kernel 7.1.11
    • Linux Kernel 7.2.1
    • Linux Kernel 7.3

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

    Metrics

    6.0

    XIEM Effective CVSS

    Highest available CVSS rating from NVD and vendor data.

    Source: Vendor (CNA), CVSS v3

    6.0

    CVSS v3

    Severity Medium on the scale from 0 to 10.

    Source: Ubuntu, HKCERT, Debian LTS, Debian, CVE.org, EUVD, Msrc Update Guide, BSI

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 10.1

    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
    54.87 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
    6.0 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
    6.0
    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
    0.2 %
    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
    10.1
    Elevated — this CVE ranks above at least 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: nilfs2: reject invalid block index in GC ioctl Syzbot reported list corruption caused by a double list_add_tail() call on bh->b_assoc_buffers within nilfs_lookup_dirty_data_buffers(). Analysis revealed that the root cause was the insertion of a page/folio with a page index of ULONG_MAX into the page cache via the GC ioctl. filemap_get_folios_tag(), called by nilfs_lookup_dirty_data_buffers(), repeatedly detects a dirty folio with a page index of ULONG_MAX due to index wrap-around, leading to duplicate processing of dirty buffers. As a preparatory step, the GC ioctl loads the page/folio of the block to be moved during GC and inserts it into the page cache based on information in the nilfs_vdesc structure passed as an argument. Normally, this does not cause issues because the user-space GC library configures the nilfs_vdesc structure properly. However, since there is no range check on the parameters determining the page index, a request with artificially crafted parameters -- such as those generated by Syzbot -- can result in a page/folio being inserted with a page index of ULONG_MAX, triggering the above problem. This resolves the issue by checking the ranges of 'vd_offset' and 'vd_vblocknr' in the nilfs_vdesc structure that determine the page index, thereby preventing the invalid page/folio insertions.

    Source: Ubuntu Security Notices, HKCERT (CC BY 3.0 HK) · HKCERT rating: medium, Debian LTS Advisories, Debian Security Advisories, cvelistv5, ENISA EUVD, NVD (NIST), CVE.org (MITRE), Microsoft Security Update Guide, 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
    • 5.11 – < 5.15.220
    • 7.2 – < 7.2.1
    • 5.16 – < 6.1.187
    • 6.7 – < 6.12.108
    • —
    • 6.13 – < 6.18.47
    • 6.19 – < 7.1.11
    • 6.2 – < 6.6.156
    • 2.6.30 – < 5.10.269
    • 5.15.220
    • 7.2.1
    • 6.1.187
    • 6.12.108
    • 7.3
    • 6.18.47
    • 7.1.11
    • 6.6.156
    • 5.10.269
    Red HatOpenShift
    • Container Platform
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxtrixie
    Linuxubuntulinuxjammy
    Linuxubuntulinuxnoble
    Linuxubuntulinuxresolute
    Linuxdebianlinux-6.12bookworm
    Linuxubuntulinux-awsjammy
    Linuxubuntulinux-awsnoble
    Linuxubuntulinux-awsresolute
    Linuxubuntulinux-aws-5.15focal
    Linuxubuntulinux-aws-6.8jammy
    Linuxubuntulinux-aws-7.0noble
    Linuxubuntulinux-aws-fipsjammy
    Linuxubuntulinux-aws-fipsnoble
    Linuxubuntulinux-azurejammy
    Linuxubuntulinux-azurenoble
    Linuxubuntulinux-azureresolute
    Linuxubuntulinux-azure-5.15focal
    Linuxubuntulinux-azure-6.8jammy
    Linuxubuntulinux-azure-fdejammy
    Linuxubuntulinux-azure-fdenoble
    Linuxubuntulinux-azure-fderesolute
    Linuxubuntulinux-azure-fde-5.15focal
    Linuxubuntulinux-azure-fde-6.8jammy

    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

      1 individual change: Affected versions (publisher)

      Show the original change
      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/2026/80xxx/CVE-2026-80807.json">CVE-2026-80807</a>

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

    2. ReceivedLinux

      Description added or changed

      Show 11 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: nilfs2: reject invalid block index in GC ioctl Syzbot reported list corruption caused by a double list_add_tail() call on bh->b_assoc_buffers within nilfs_lookup_dirty_data_buffers(). Analysis revealed that the root cause was the insertion of a page/folio with a page index of ULONG_MAX into the page cache via the GC ioctl. filemap_get_folios_tag(), called by nilfs_lookup_dirty_data_buffers(), repeatedly detects a dirty folio with a page index of ULONG_MAX due to index wrap-around, leading to duplicate processing of dirty buffers. As a preparatory step, the GC ioctl loads the page/folio of the block to be moved during GC and inserts it into the page cache based on information in the nilfs_vdesc structure passed as an argument. Normally, this does not cause issues because the user-space GC library configures the nilfs_vdesc structure properly. However, since there is no range check on the parameters determining the page index, a request with artificially crafted parameters -- such as those generated by Syzbot -- can result in a page/folio being inserted with a page index of ULONG_MAX, triggering the above problem. This resolves the issue by checking the ranges of 'vd_offset' and 'vd_vblocknr' in the nilfs_vdesc structure that determine the page index, thereby preventing the invalid page/folio insertions.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/80xxx/CVE-2026-80807.json">CVE-2026-80807</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/3bd064ccc70b85f9a3d53aece29dc8473be5a226
      Referenceadded
      —
      https://git.kernel.org/stable/c/68aa9ab6f8f2895713aa6ddf781463ed8ea5ba44
      Referenceadded
      —
      https://git.kernel.org/stable/c/898404cdf882d7b54f1132f75570984ca3214796
      Referenceadded
      —
      https://git.kernel.org/stable/c/a1735eae55448bc79c2da6593455791e886f6ed8
      Referenceadded
      —
      https://git.kernel.org/stable/c/a5e776e2937581d67ec5b9b4d27b0f70d7baa6b1
      Referenceadded
      —
      https://git.kernel.org/stable/c/ba8a8b563a28d358c45c62a306d421434a058648
      Referenceadded
      —
      https://git.kernel.org/stable/c/e447f7edb99bd00cec63d6f3049e2e5074946f71
      Referenceadded
      —
      https://git.kernel.org/stable/c/ec6ddf271dfa4c7e3147bc2c8b2bad4315f316a1
      Referenceadded
      —
      https://git.kernel.org/stable/c/fbcfb75c20d71a5b542ad4ac3b79d10b997c8152

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

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