MediumCVE-2026-99035

    Linux Kernel: Use-After-Free (CVE-2026-99035)

    Published Last modified Sources: BSI, Msrc Update Guide, CVE.org

    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: mmc: mtk-sd: Cancel request timeout work on remove The driver queues req_timeout while a request is active. msdc_request_done() uses cancel_delayed_work(), which does not wait for a timeout callback that has already started. The timeout callback calls mmc_request_done(), which wakes the request waiter, and then continues to use host->dev_comp and check the SDIO IRQ.

    Update Linux Kernel to version 5.10.273, Linux Kernel to version 5.15.224, Linux Kernel to version 6.1.191.

    Affected
    • Linux Kernel lt 4.2..5.10.273
    • Linux Kernel lt 5.11..5.15.224
    • Linux Kernel lt 5.16..6.1.191
    • Linux Kernel lt 6.2..6.6.160
    • Linux Kernel lt 6.7..6.12.113
    • Linux Kernel lt 6.13..6.18.57
    • Linux Kernel lt 6.19..7.2.11
    Fixed in
    • Linux Kernel 5.10.273
    • Linux Kernel 5.15.224
    • Linux Kernel 6.1.191
    • Linux Kernel 6.6.160
    • Linux Kernel 6.12.113
    • Linux Kernel 6.18.57
    • Linux Kernel 7.2.11
    • Linux Kernel 7.3

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

    Metrics

    4.7

    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: BSI, Msrc Update Guide, CVE.org

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 6.2

    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
    53.80 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
    4.7 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
    0.2 %
    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
    6.2
    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: mmc: mtk-sd: Cancel request timeout work on remove The driver queues req_timeout while a request is active. msdc_request_done() uses cancel_delayed_work(), which does not wait for a timeout callback that has already started. The timeout callback calls mmc_request_done(), which wakes the request waiter, and then continues to use host->dev_comp and check the SDIO IRQ. During unbind, msdc_drv_remove() can return and the managed mmc_host can be freed before the callback finishes. KASAN reported use-after-free accesses in msdc_request_done() and msdc_recheck_sdio_irq() in each of three unbind tests. The same tests completed without a kernel diagnostic after this change. Call cancel_delayed_work_sync() after mmc_remove_host() has stopped new requests and before the driver releases the host resources.

    Source: BSI CSAF, BSI WID Portal, Microsoft Security Update Guide, cvelistv5, NVD (NIST)

    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
    • 6.19 – < 7.2.11
    • 5.11 – < 5.15.224
    • 5.16 – < 6.1.191
    • 6.7 – < 6.12.113
    • —
    • 6.13 – < 6.18.57
    • 4.2 – < 5.10.273
    • 6.2 – < 6.6.160
    • 7.2.11
    • 5.15.224
    • 6.1.191
    • 6.12.113
    • 7.3
    • 6.18.57
    • 5.10.273
    • 6.6.160

    Vendors and products

    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 4 original changes
      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/2026/99xxx/CVE-2026-99035.json">CVE-2026-99035</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/2cff6a2a912a3464ae1fefb7e0a82393682ccea6
      Referenceadded
      —
      https://git.kernel.org/stable/c/d8ce81006ee4e42ce2d0bd3a2ab87adc1e24ef11
      Referenceadded
      —
      https://git.kernel.org/stable/c/e5d82695f2cabca3222b8f6a89ea0e18bafc4c0a

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

    2. ReceivedLinux

      Description added or changed

      Show 7 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: mmc: mtk-sd: Cancel request timeout work on remove The driver queues req_timeout while a request is active. msdc_request_done() uses cancel_delayed_work(), which does not wait for a timeout callback that has already started. The timeout callback calls mmc_request_done(), which wakes the request waiter, and then continues to use host->dev_comp and check the SDIO IRQ. During unbind, msdc_drv_remove() can return and the managed mmc_host can be freed before the callback finishes. KASAN reported use-after-free accesses in msdc_request_done() and msdc_recheck_sdio_irq() in each of three unbind tests. The same tests completed without a kernel diagnostic after this change. Call cancel_delayed_work_sync() after mmc_remove_host() has stopped new requests and before the driver releases the host resources.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/99xxx/CVE-2026-99035.json">CVE-2026-99035</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/46e75703ca3f00fb8c935b3ce35b90836e34e8af
      Referenceadded
      —
      https://git.kernel.org/stable/c/9e799f25c420e759641eb25102967ea091fc758f
      Referenceadded
      —
      https://git.kernel.org/stable/c/b38af5386a74416e898955443f2e26547b358cb2
      Referenceadded
      —
      https://git.kernel.org/stable/c/edef1355224c0799a502a46b71d3649fa0dd218e
      Referenceadded
      —
      https://git.kernel.org/stable/c/f37e0367ad6f2147a0b37564b442b7a25bec0d23

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

    Embed badge

    Show the severity and KEV status of this vulnerability on your site – with a link back here. The image is updated hourly.

    Badge preview for CVE-2026-99035
    <a href="https://intel.neosec.eu/en/cve/CVE-2026-99035"><img src="https://intel.neosec.eu/badge/cve/CVE-2026-99035.svg?lang=en" alt="CVE-2026-99035 – NEOSEC Intel" height="20"></a>