MediumCVE-2026-46159

    Linux Kernel: security vulnerability (CVE-2026-46159)

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

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak btrfs_ioctl_space_info() has a TOCTOU race between two passes over the block group RAID type lists. The first pass counts entries to determine the allocation size, then the second pass fills the buffer.

    Update Linux Kernel to version 5.10.259, Linux Kernel to version 5.15.210, Linux Kernel to version 6.1.176.

    Affected
    • Linux Kernel lt 2.6.34..5.10.259
    • Linux Kernel lt 5.11..5.15.210
    • Linux Kernel lt 5.16..6.1.176
    • Linux Kernel lt 6.2..6.6.140
    • Linux Kernel lt 6.7..6.12.90
    • Linux Kernel lt 6.13..6.18.32
    • Linux Kernel lt 6.19..7.0.7
    Fixed in
    • Linux Kernel 5.10.259
    • Linux Kernel 5.15.210
    • Linux Kernel 6.1.176
    • Linux Kernel 6.6.140
    • Linux Kernel 6.12.90
    • Linux Kernel 6.18.32
    • Linux Kernel 7.0.7
    • Linux Kernel 7.1

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

    Metrics

    5.5

    Priority

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

    Source: Vendor (CNA), CVSS v3

    4.7

    CVSS v3

    Severity Medium on the scale from 0 to 10.

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

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 0.7

    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
    41.29 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
    5.5 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
    4.7
    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
    0.7
    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

    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: btrfs: fix btrfs_ioctl_space_info() slot_count TOCTOU which can lead to info-leak btrfs_ioctl_space_info() has a TOCTOU race between two passes over the block group RAID type lists. The first pass counts entries to determine the allocation size, then the second pass fills the buffer. The groups_sem rwlock is released between passes, allowing concurrent block group removal to reduce the entry count. When the second pass fills fewer entries than the first pass counted, copy_to_user() copies the full alloc_size bytes including trailing uninitialized kmalloc bytes to userspace. Fix by copying only total_spaces entries (the actually-filled count from the second pass) instead of alloc_size bytes, and switch to kzalloc so any future copy size mismatch cannot leak heap data.

    Source: Debian LTS Advisories, suse_csaf, Ubuntu Security Notices, siemens_advisory, BSI WID Portal, BSI CSAF, Microsoft Security Update Guide, cvelistv5, NVD (NIST), ENISA EUVD, CVE.org (MITRE)

    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
    • 6.2 – < 6.6.140
    • 5.11 – < 5.15.210
    • 6.19 – < 7.0.7
    • 6.13 – < 6.18.32
    • 2.6.34 – < 5.10.259
    • —
    • 6.7 – < 6.12.90
    • 5.16 – < 6.1.176
    • 6.6.140
    • 5.15.210
    • 7.0.7
    • 6.18.32
    • 5.10.259
    • 7.1
    • 6.12.90
    • 6.1.176
    SiemensSIMATIC S7
    • 1500 TM MFP V1.1.1 GNU/Linux subsystem
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxbullseye
    Linuxdebianlinux-6.1bullseye
    Linuxubuntulinux-nvidiajammy
    Linuxubuntulinux-nvidia-tegrajammy
    Linuxubuntulinux-nvidia-tegra-5.15focal
    Linuxubuntulinux-nvidia-tegra-igxjammy
    Linuxlinuxlinux_kernel2.6.34
    Linuxlinuxlinux_kernel—

    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 21 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3
      Referenceadded
      —
      https://git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088
      Referenceadded
      —
      https://git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77
      Referenceadded
      —
      https://git.kernel.org/stable/c/d09d67d5de577cedae3de9497dff217e0ac8b641
      Referenceadded
      —
      https://git.kernel.org/stable/c/d69a4a6813fdba7c4cc3695a7e843842b240790d
      Referenceadded
      —
      https://git.kernel.org/stable/c/d8224b1be6627c6c3b204bfb264508d27c65ac44
      Referenceadded
      —
      https://git.kernel.org/stable/c/f407aad350bdea4db300c47433573b7a41630d33
      Referenceadded
      —
      https://git.kernel.org/stable/c/f5ee467b56764964027c361641f64953fc0f8f9a
      Referenceremoved
      https://git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3
      —
      Referenceremoved
      https://git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088
      —
      Referenceremoved
      https://git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d09d67d5de577cedae3de9497dff217e0ac8b641
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d69a4a6813fdba7c4cc3695a7e843842b240790d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d8224b1be6627c6c3b204bfb264508d27c65ac44
      —
      Referenceremoved
      https://git.kernel.org/stable/c/f407aad350bdea4db300c47433573b7a41630d33
      —
      Referenceremoved
      https://git.kernel.org/stable/c/f5ee467b56764964027c361641f64953fc0f8f9a
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/4fdc6ee0802121d9cd96b8d085e589f51e5a4ec3 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/5d12e0ab009ade48c1bff9324fd9bea2c773d088 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/973e57c726c1f8e77259d1c8e519519f1e9aea77 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/d09d67d5de577cedae3de9497dff217e0ac8b641 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/f5ee467b56764964027c361641f64953fc0f8f9a Types: Patch
      —

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

    2. 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/2026/46xxx/CVE-2026-46159.json">CVE-2026-46159</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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

    3. Record modifiedLinux

      Show 4 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/d69a4a6813fdba7c4cc3695a7e843842b240790d
      Referenceadded
      —
      https://git.kernel.org/stable/c/d8224b1be6627c6c3b204bfb264508d27c65ac44
      Referenceadded
      —
      https://git.kernel.org/stable/c/f407aad350bdea4db300c47433573b7a41630d33
      Affected versions (publisher)changed
      Linux, Linux
      Linux, Linux

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

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