MediumCVE-2026-98837

    Linux Kernel: Use-After-Free (CVE-2026-98837)

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

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    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: unregister the input device when probe fails setup_card() registers the input device, whose name and phys point into struct snd_usb_caiaqdev, and then goes on to snd_card_register() and snd_usb_caiaq_control_init(). If either fails, snd_probe() calls snd_card_free(), which frees the device state but leaves the input device registered: card_free() only clears the pointer, and the input device is unregistered from snd_disconnect() alone.

    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

    4.6

    Priority

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

    Source: Vendor (CNA), CVSS v3

    4.6

    CVSS v3

    Severity Medium on the scale from 0 to 10.

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

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 11.3

    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
    54.01 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
    4.6 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
    4.6
    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
    11.3
    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: ALSA: caiaq: unregister the input device when probe fails setup_card() registers the input device, whose name and phys point into struct snd_usb_caiaqdev, and then goes on to snd_card_register() and snd_usb_caiaq_control_init(). If either fails, snd_probe() calls snd_card_free(), which frees the device state but leaves the input device registered: card_free() only clears the pointer, and the input device is unregistered from snd_disconnect() alone. Reading its "uevent" attribute afterwards dereferences freed memory: BUG: KASAN: slab-use-after-free in string+0x4a9/0x4f0 Read of size 1 at addr ffff8880208f5043 by task caiaq/4967 add_uevent_var+0x183/0x3a0 input_dev_uevent+0x162/0x900 dev_uevent+0x2f1/0x870 uevent_show+0x1ca/0x3a0 ... Unregister the input device on the probe error path, as snd_disconnect() does. snd_usb_caiaq_input_disconnect() is a no-op when no input device was registered. Reproduced with a raw-gadget Audio Kontrol 1 and a temporary hack that makes snd_usb_caiaq_control_init() fail.

    Source: Debian LTS Advisories, BSI WID Portal, BSI CSAF, 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
    • 5.15.209 – < 5.15.224
    • 5.10.258 – < 5.10.273
    • 6.1.175 – < 6.1.191
    • —
    • 6.12.86 – < 6.12.113
    • 6.18.27 – < 6.18.56
    • 6.6.140 – < 6.6.160
    • 7.0.4 – < 7.1
    • 7.1 – < 7.2.10
    • 5.15.224
    • 5.10.273
    • 6.1.191
    • 7.3
    • 6.12.113
    • 6.18.56
    • 6.6.160
    • 7.1
    • 7.2.10

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinux-6.12bookworm

    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/2026/98xxx/CVE-2026-98837.json">CVE-2026-98837</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/1d5d194594ff616ad36a052bde739d1cf5855b95
      Referenceadded
      —
      https://git.kernel.org/stable/c/7017c9dda1ebbab428a6fd29c841596b5c9c84d1
      Referenceadded
      —
      https://git.kernel.org/stable/c/8315ea07ebb2497531ff42dd640396f6f1d4a8f0

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

    2. Record modifiedLinux

      Show 2 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/2026/98xxx/CVE-2026-98837.json">CVE-2026-98837</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/df2787819bd137111b56b8631dd581b0cce7144d

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

    3. 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/2026/98xxx/CVE-2026-98837.json">CVE-2026-98837</a>

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

    4. ReceivedLinux

      Description added or changed

      Show 6 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
      —
      In the Linux kernel, the following vulnerability has been resolved: ALSA: caiaq: unregister the input device when probe fails setup_card() registers the input device, whose name and phys point into struct snd_usb_caiaqdev, and then goes on to snd_card_register() and snd_usb_caiaq_control_init(). If either fails, snd_probe() calls snd_card_free(), which frees the device state but leaves the input device registered: card_free() only clears the pointer, and the input device is unregistered from snd_disconnect() alone. Reading its "uevent" attribute afterwards dereferences freed memory: BUG: KASAN: slab-use-after-free in string+0x4a9/0x4f0 Read of size 1 at addr ffff8880208f5043 by task caiaq/4967 add_uevent_var+0x183/0x3a0 input_dev_uevent+0x162/0x900 dev_uevent+0x2f1/0x870 uevent_show+0x1ca/0x3a0 ... Unregister the input device on the probe error path, as snd_disconnect() does. snd_usb_caiaq_input_disconnect() is a no-op when no input device was registered. Reproduced with a raw-gadget Audio Kontrol 1 and a temporary hack that makes snd_usb_caiaq_control_init() fail.
      Affected versions (publisher)added
      —
      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/98xxx/CVE-2026-98837.json">CVE-2026-98837</a>
      Referenceadded
      —
      https://git.kernel.org/stable/c/0b7bd20f6379bc5e431fd74d866390f5b5b63f3c
      Referenceadded
      —
      https://git.kernel.org/stable/c/2e5a413cc2a489c9427ecd3d73ad764bfb0c7103
      Referenceadded
      —
      https://git.kernel.org/stable/c/84727facd8506140cd04f2b0a8b1c4ddeac41cea
      Referenceadded
      —
      https://git.kernel.org/stable/c/850810c12686f80cdf7530f4f21e0157d904f739

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

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