HighCVE-2026-46124

    Linux Kernel: security vulnerability (CVE-2026-46124)

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

    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: isofs: validate block number from NFS file handle in isofs_export_iget isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker- controlled block number (ifid->block or ifid->parent_block) from the NFS file handle to isofs_export_iget(), which only rejects block == 0 before calling isofs_iget() and ultimately sb_bread(). A crafted file handle with fh_len sufficient to pass the check added by commit 0405d4b63d08 ("isofs: Prevent the use of too small fid") can still drive the server to read any in-range block on the backing device as if it were an iso_directory_record.

    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

    7.5

    Priority

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

    Source: Vendor (CNA), CVSS v3

    7.5

    CVSS v3

    Severity High on the scale from 0 to 10.

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

    0.5 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 41.1

    Show all metrics
    Severity
    High
    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
    69.01 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
    7.5 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
    7.5
    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
    41.1
    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: partial
    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-125

    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: isofs: validate block number from NFS file handle in isofs_export_iget isofs_fh_to_dentry() and isofs_fh_to_parent() pass an attacker- controlled block number (ifid->block or ifid->parent_block) from the NFS file handle to isofs_export_iget(), which only rejects block == 0 before calling isofs_iget() and ultimately sb_bread(). A crafted file handle with fh_len sufficient to pass the check added by commit 0405d4b63d08 ("isofs: Prevent the use of too small fid") can still drive the server to read any in-range block on the backing device as if it were an iso_directory_record. That earlier fix was assigned CVE-2025-37780. sb_bread() on an out-of-range block returns NULL cleanly via the EIO path, so there is no memory-safety violation. For in-range reads of adjacent-partition data on the same block device, the unrelated bytes end up in iso_inode_info fields that reach the NFS client as dentry metadata. The deployment surface (isofs exported over NFS from loop-mounted images) is narrow and requires an authenticated NFS peer, but the malformed-file-handle class is reportable as hardening next to the existing CVE-2025-37780 fix. Reject block >= ISOFS_SB(sb)->s_nzones in isofs_export_iget() so the check covers both isofs_fh_to_dentry() and isofs_fh_to_parent() call sites with a single line.

    Source: Debian LTS Advisories, suse_csaf, Ubuntu Security Notices, siemens_advisory, Microsoft Security Update Guide, ENISA EUVD, 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
    • 5.10.237 – < 5.10.258
    • 6.12.25 – < 6.12.88
    • 6.6.88 – < 6.6.140
    • 6.1.135 – < 6.1.175
    • 6.15 – < 6.18.30
    • 6.19 – < 7.0.7
    • 6.14.4 – < 6.15
    • —
    • 5.15.181 – < 5.15.209
    • 5.4.293 – < 5.5
    • 5.10.258
    • 6.12.88
    • 6.6.140
    • 6.1.175
    • 6.18.30
    • 7.0.7
    • 6.15
    • 7.1
    • 5.15.209
    • 5.5
    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
    Linuxlinuxlinux_kernel6.15
    Linuxlinuxlinux_kernel7.1
    Linuxlinuxlinux_kernel—

    Weakness classes (CWE)

    • CWE-125Out-of-bounds Read

      Base

      The product reads data past the end, or before the beginning, of the intended buffer.

      Entry at MITRE CWE-125

    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-125

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-125

      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-2026-46124","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"yes"},{"technicalImpact":"partial"}],"version":"2.0.3","timestamp":"2026-10-16T15:20:06.239084Z"}

      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/0a1af74ae2177bda3aee0837a0546309aa539d0d
      Referenceadded
      —
      https://git.kernel.org/stable/c/24376458138387fb251e782e624c7776e9826796
      Referenceadded
      —
      https://git.kernel.org/stable/c/31dbb4ba0f719ae7774e4c0c95172c9bf81692f5
      Referenceadded
      —
      https://git.kernel.org/stable/c/4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6
      Referenceadded
      —
      https://git.kernel.org/stable/c/908a76f0b1038035e6ebb4f2293ce079f92e0a02
      Referenceadded
      —
      https://git.kernel.org/stable/c/afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b
      Referenceadded
      —
      https://git.kernel.org/stable/c/bb0988ed4f2e26d59bbb58f644cb3a55b7521e21
      Referenceadded
      —
      https://git.kernel.org/stable/c/ee0024f5a7e3c73aa253869fae9650ae054093ca
      Referenceremoved
      https://git.kernel.org/stable/c/0a1af74ae2177bda3aee0837a0546309aa539d0d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/24376458138387fb251e782e624c7776e9826796
      —
      Referenceremoved
      https://git.kernel.org/stable/c/31dbb4ba0f719ae7774e4c0c95172c9bf81692f5
      —
      Referenceremoved
      https://git.kernel.org/stable/c/4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6
      —
      Referenceremoved
      https://git.kernel.org/stable/c/908a76f0b1038035e6ebb4f2293ce079f92e0a02
      —
      Referenceremoved
      https://git.kernel.org/stable/c/afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b
      —
      Referenceremoved
      https://git.kernel.org/stable/c/bb0988ed4f2e26d59bbb58f644cb3a55b7521e21
      —
      Referenceremoved
      https://git.kernel.org/stable/c/ee0024f5a7e3c73aa253869fae9650ae054093ca
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/0a1af74ae2177bda3aee0837a0546309aa539d0d Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/24376458138387fb251e782e624c7776e9826796 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/31dbb4ba0f719ae7774e4c0c95172c9bf81692f5 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/908a76f0b1038035e6ebb4f2293ce079f92e0a02 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/bb0988ed4f2e26d59bbb58f644cb3a55b7521e21 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/ee0024f5a7e3c73aa253869fae9650ae054093ca Types: Patch
      —

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

    4. 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-2026-46124.json">CVE-2026-46124</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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

    5. Initial analysis by NVDNVD

      Newly listed as affected:
      • Linux Kernel (6.14.4 – before 6.15; 5.4.293 – before 5.5; 6.19 – before 7.0.7; 5.10.237 – before 5.10.258; 5.15.181 – before 5.15.209; 6.1.135 – before 6.1.175; 6.6.88 – before 6.6.140; 6.12.25 – before 6.12.88; 6.15.1 – before 6.18.30; 7 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:6.15:rc3:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:rc7:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.15:-:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.14.4 up to (excluding) 6.15 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.4.293 up to (excluding) 5.5 *cpe:2.3:o:linux:linux_kernel:7.1:rc1:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.19 up to (excluding) 7.0.7 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.10.237 up to (excluding) 5.10.258 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 5.15.181 up to (excluding) 5.15.209 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.1.135 up to (excluding) 6.1.175 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.6.88 up to (excluding) 6.6.140 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.12.25 up to (excluding) 6.12.88 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.15.1 up to (excluding) 6.18.30
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/0a1af74ae2177bda3aee0837a0546309aa539d0d Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/24376458138387fb251e782e624c7776e9826796 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/31dbb4ba0f719ae7774e4c0c95172c9bf81692f5 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/4c721a1d9b3c4fcaf59cc9b2281e3ec5a043e1a6 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/908a76f0b1038035e6ebb4f2293ce079f92e0a02 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/afbafeddf23db13fe2edb2d5c0bf4bbb13d7881b Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/bb0988ed4f2e26d59bbb58f644cb3a55b7521e21 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/ee0024f5a7e3c73aa253869fae9650ae054093ca Types: Patch

      Source identifier: nvd@nist.gov

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