HighCVE-2026-53265

    Linux Kernel: security vulnerability (CVE-2026-53265)

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

    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: dm cache policy smq: check allocation under invalidate lock commit 2d1f7b65f5de ("dm cache policy smq: fix missing locks in invalidating cache blocks") added mq->lock around the destructive part of smq_invalidate_mapping(), but left the e->allocated check outside the critical section. That leaves a check-then-act race.

    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 5.10.258..5.10.259
    • Linux Kernel lt 5.15.209..5.15.210
    • Linux Kernel lt 6.1.175..6.1.176
    • Linux Kernel lt 6.6.141..6.6.143
    • Linux Kernel lt 6.12.91..6.12.94
    • Linux Kernel lt 6.18.33..6.18.36
    • Linux Kernel lt 7.0.10..7.0.13
    Fixed in
    • Linux Kernel 5.10.259
    • Linux Kernel 5.15.210
    • Linux Kernel 6.1.176
    • Linux Kernel 6.6.143
    • Linux Kernel 6.12.94
    • Linux Kernel 6.18.36
    • Linux Kernel 7.0.13

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

    Metrics

    7.8

    Priority

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

    Source: Vendor (CNA), CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

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

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 0.8

    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
    58.52 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
    7.8 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
    7.8
    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
    0.1 %
    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
    0.8
    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
    CISA assessment (SSVC)
    Exploitation: none known · not 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-362

    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: dm cache policy smq: check allocation under invalidate lock commit 2d1f7b65f5de ("dm cache policy smq: fix missing locks in invalidating cache blocks") added mq->lock around the destructive part of smq_invalidate_mapping(), but left the e->allocated check outside the critical section. That leaves a check-then-act race. Two concurrent invalidators can both observe e->allocated as true before either of them takes mq->lock. The first invalidator that acquires the lock removes the entry from the queues and hash table and then calls free_entry(), which clears e->allocated and puts the entry back on the free list. The second invalidator can then acquire mq->lock and continue with the stale result of the unlocked check. This can corrupt the SMQ queues or hash table by deleting an entry that is no longer on those structures. It can also hit the allocation check in free_entry() when the same entry is freed again. Move the allocation check under mq->lock so the predicate and the destructive operations are serialized by the same lock.

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

    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
    • 5.15.209 – < 5.15.210
    • 6.18.33 – < 6.18.36
    • 5.10.258 – < 5.10.259
    • 6.1.175 – < 6.1.176
    • 7.0.10 – < 7.0.13
    • 6.12.91 – < 6.12.94
    • 6.6.141 – < 6.6.143
    • 5.15.210
    • 6.18.36
    • 5.10.259
    • 6.1.176
    • 7.0.13
    • 6.12.94
    • 6.6.143
    SiemensSIMATIC S7
    • 1500 TM MFP V1.1.1 GNU/Linux subsystem
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxlinuxlinux_kernel5.10.258
    Linuxlinuxlinux_kernel5.15.209
    Linuxlinuxlinux_kernel6.1.175
    Linuxlinuxlinux_kernel7.1
    Linuxlinuxlinux_kernel—

    Weakness classes (CWE)

    • CWE-362Concurrent Execution using Shared Resource with Improper Synchronization ('Race Condition')

      Class

      The product contains a concurrent code sequence that requires temporary, exclusive access to a shared resource, but a timing window exists in which the shared resource can be modified by another code sequence operating concurrently.

      Entry at MITRE CWE-362

    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-362

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Weakness type (CWE)added
      —
      CWE-362

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

    2. Record modifiedCISA ADP

      CISA assessment (SSVC): exploitation: none known, automatable: no

      Show the original change
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      SSVC assessmentadded
      —
      {"id":"CVE-2026-53265","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:28:01.536149Z"}

      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/03ffe1112ed88bb3a9bd0b971549bf4d64bfc59a
      Referenceadded
      —
      https://git.kernel.org/stable/c/13da856c86fb8c2ccab95034fd77da1bb2c2a17c
      Referenceadded
      —
      https://git.kernel.org/stable/c/42ff6774ecd9d7f70d599cb71ff64373a1da4948
      Referenceadded
      —
      https://git.kernel.org/stable/c/b4892561552d671bd8c4da5ebb70e9fbb1ec446e
      Referenceadded
      —
      https://git.kernel.org/stable/c/c242c7af2aecf0b538b8623bdb86b8b441da38d9
      Referenceadded
      —
      https://git.kernel.org/stable/c/c57570fba24016ec25ec046ab44db39143fb7a64
      Referenceadded
      —
      https://git.kernel.org/stable/c/d3f0a606b9f278ece8a0df626ded9c4044071235
      Referenceadded
      —
      https://git.kernel.org/stable/c/d886945fcb0f8c9dc6b39928d7a96c95c587346c
      Referenceremoved
      https://git.kernel.org/stable/c/03ffe1112ed88bb3a9bd0b971549bf4d64bfc59a
      —
      Referenceremoved
      https://git.kernel.org/stable/c/13da856c86fb8c2ccab95034fd77da1bb2c2a17c
      —
      Referenceremoved
      https://git.kernel.org/stable/c/42ff6774ecd9d7f70d599cb71ff64373a1da4948
      —
      Referenceremoved
      https://git.kernel.org/stable/c/b4892561552d671bd8c4da5ebb70e9fbb1ec446e
      —
      Referenceremoved
      https://git.kernel.org/stable/c/c242c7af2aecf0b538b8623bdb86b8b441da38d9
      —
      Referenceremoved
      https://git.kernel.org/stable/c/c57570fba24016ec25ec046ab44db39143fb7a64
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d3f0a606b9f278ece8a0df626ded9c4044071235
      —
      Referenceremoved
      https://git.kernel.org/stable/c/d886945fcb0f8c9dc6b39928d7a96c95c587346c
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/03ffe1112ed88bb3a9bd0b971549bf4d64bfc59a Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/13da856c86fb8c2ccab95034fd77da1bb2c2a17c Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/42ff6774ecd9d7f70d599cb71ff64373a1da4948 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/b4892561552d671bd8c4da5ebb70e9fbb1ec446e Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/c242c7af2aecf0b538b8623bdb86b8b441da38d9 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/c57570fba24016ec25ec046ab44db39143fb7a64 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/d3f0a606b9f278ece8a0df626ded9c4044071235 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/d886945fcb0f8c9dc6b39928d7a96c95c587346c 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/2026/53xxx/CVE-2026-53265.json">CVE-2026-53265</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 (7.0.10 – before 7.0.13; 6.12.91 – before 6.12.94; 6.18.33 – before 6.18.36; 6.6.141 – before 6.6.143; 9 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: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:7.1:rc4:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc5:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:7.1:rc6:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 7.0.10 up to (excluding) 7.0.13 *cpe:2.3:o:linux:linux_kernel:5.15.209:*:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.12.91 up to (excluding) 6.12.94 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.18.33 up to (excluding) 6.18.36 *cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:* versions from (including) 6.6.141 up to (excluding) 6.6.143 *cpe:2.3:o:linux:linux_kernel:5.10.258:*:*:*:*:*:*:* *cpe:2.3:o:linux:linux_kernel:6.1.175:*:*:*:*:*:*:*
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/03ffe1112ed88bb3a9bd0b971549bf4d64bfc59a Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/13da856c86fb8c2ccab95034fd77da1bb2c2a17c Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/42ff6774ecd9d7f70d599cb71ff64373a1da4948 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/b4892561552d671bd8c4da5ebb70e9fbb1ec446e Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/c242c7af2aecf0b538b8623bdb86b8b441da38d9 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/c57570fba24016ec25ec046ab44db39143fb7a64 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/d3f0a606b9f278ece8a0df626ded9c4044071235 Types: Patch
      Reference typeadded
      —
      kernel.org: https://git.kernel.org/stable/c/d886945fcb0f8c9dc6b39928d7a96c95c587346c Types: Patch

      Source identifier: nvd@nist.gov

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