HighCVE-2026-46275

    Linux Kernel: Race Condition (CVE-2026-46275)

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

    What is affected, what to do

    A flaw was found in the Linux kernel's Bluetooth hci_uart component. Lifecycle management issues, including Use-After-Free (UAF) and race conditions, were identified during the closing and initialization paths.

    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.

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    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, Debian LTS, Ubuntu, Siemens ProductCERT, Red Hat, Debian, BSI, CVE.org, Msrc Update Guide

    0.2 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 13.2

    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
    59.06 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.

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    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.

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    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“.

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    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.

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    13.2
    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.

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    —
    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
    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

    A flaw was found in the Linux kernel's Bluetooth hci_uart component. Lifecycle management issues, including Use-After-Free (UAF) and race conditions, were identified during the closing and initialization paths. These issues can lead to the dereferencing of freed memory, potentially causing system instability, crashes, or arbitrary code execution.

    Source: suse_csaf, Debian LTS Advisories, Ubuntu Security Notices, siemens_advisory, redhat_csaf, Debian Security Advisories, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), Microsoft Security Update Guide, 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
    • 5.16 – < 6.1.175
    • 5.10 – < 5.10.258
    • 6.19 – < 7.0.11
    • 4.14.203 – < 4.15
    • 5.4.73 – < 5.5
    • 6.13 – < 6.18.34
    • 5.11 – < 5.15.209
    • 4.19.153 – < 4.20
    • 5.9.2 – < 5.10
    • —
    • 5.8.17 – < 5.9
    • 6.7 – < 6.12.92
    • 6.2 – < 6.6.142
    • 6.1.175
    • 5.10.258
    • 7.0.11
    • 4.15
    • 5.5
    • 6.18.34
    • 5.15.209
    • 4.20
    • 5.10
    • 7.1
    • 5.9
    • 6.12.92
    • 6.6.142
    SiemensSIMATIC S7
    • 1500 TM MFP V1.1.1 GNU/Linux subsystem
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxbullseye
    Linuxdebianlinuxtrixie
    Linuxdebianlinux-6.1bullseye
    Linuxubuntulinux-aws-fipsnoble
    Linuxlinuxlinux_kernel7.1
    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 modifiedCISA ADP

      Weakness type: CWE-362

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      TypeActionBeforeAfter
      Weakness type (CWE)added
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      CWE-362

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

    2. Record modifiedCISA ADP

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

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      TypeActionBeforeAfter
      SSVC assessmentadded
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      {"id":"CVE-2026-46275","role":"CISA Coordinator","options":[{"exploitation":"none"},{"automatable":"no"},{"technicalImpact":"total"}],"version":"2.0.3","timestamp":"2026-10-16T15:21:36.754865Z"}

      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
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      https://git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894
      Referenceadded
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      https://git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8
      Referenceadded
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      https://git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c
      Referenceadded
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      https://git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d
      Referenceadded
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      https://git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34
      Referenceadded
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      https://git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b
      Referenceadded
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      https://git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6
      Referenceadded
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      https://git.kernel.org/stable/c/e2d19969c8d9198ecc3090bcd5312ecd503a3339
      Referenceremoved
      https://git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894
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      Referenceremoved
      https://git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8
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      Referenceremoved
      https://git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c
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      Referenceremoved
      https://git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d
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      Referenceremoved
      https://git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34
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      https://git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b
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      Referenceremoved
      https://git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6
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      Referenceremoved
      https://git.kernel.org/stable/c/e2d19969c8d9198ecc3090bcd5312ecd503a3339
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      Reference typeremoved
      https://git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894 Types: Patch
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      Reference typeremoved
      https://git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8 Types: Patch
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      Reference typeremoved
      https://git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c Types: Patch
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      Reference typeremoved
      https://git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d Types: Patch
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      Reference typeremoved
      https://git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34 Types: Patch
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      Reference typeremoved
      https://git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b Types: Patch
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      Reference typeremoved
      https://git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/e2d19969c8d9198ecc3090bcd5312ecd503a3339 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
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      New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/46xxx/CVE-2026-46275.json">CVE-2026-46275</a>
      Referenceadded
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      https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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

    5. ReceivedLinux

      Description added or changed

      Show 9 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Descriptionadded
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      In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths Vulnerabilities leading to Use-After-Free (UAF) and Null Pointer Dereference (NPD) conditions were observed in the lifecycle management of hci_uart. The primary issue arises because the workqueues (init_ready and write_work) are only flushed/cancelled if the HCI_UART_PROTO_READY flag is set during TTY close. If a hangup occurs before setup completes, hci_uart_tty_close() skips the teardown of these workqueues and proceeds to free the `hu` struct. When the scheduled work executes later, it blindly dereferences the freed `hu` struct. Furthermore, several data races and UAFs were identified in the teardown sequence: 1. Calling hci_uart_flush() from hci_uart_close() without effectively disabling write_work causes a race condition where both can concurrently double-free hu->tx_skb. This happens because protocol timers can concurrently invoke hci_uart_tx_wakeup() and requeue write_work. 2. Calling hci_free_dev(hdev) before hu->proto->close(hu) causes a UAF when vendor specific protocol close callbacks dereference hu->hdev. 3. In the initialization error paths, failing to take the proto_lock write lock before clearing PROTO_READY leads to races with active readers. Additionally, hci_uart_tty_receive() accesses hu->hdev outside the read lock, leading to UAFs if the initialization error path frees hdev concurrently. Fix these synchronization and lifecycle issues by: 1. Re-ordering hci_uart_tty_close() to clear HCI_UART_PROTO_READY first, followed immediately by a cancel_work_sync(&hu->write_work). Clearing the flag locks out concurrent protocol timers from successfully invoking hci_uart_tx_wakeup(), effectively rendering the cancellation permanent and preventing the tx_skb double-free. 2. Note: Clearing PROTO_READY early causes hci_uart_close() to skip hu->proto->flush(). This is perfectly safe in the tty_close path because hu->proto->close() executes shortly after, which intrinsically purges all protocol SKB queues and tears down the state. 3. Relocating hu->proto->close(hu) strictly prior to hci_free_dev(hdev) across all close and error paths to prevent vendor-level UAFs. 4. Moving the hdev->stat.byte_rx increment in hci_uart_tty_receive() inside the proto_lock read-side critical section to safely synchronize with device unregistration. 5. Adding cancel_work_sync(&hu->write_work) to hci_uart_close() to safely flush the workqueue before hci_uart_flush() is invoked via the HCI core. 6. Utilizing cancel_work_sync() instead of disable_work_sync() across all paths to prevent permanently breaking user-space retry capabilities.
      Referenceadded
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      https://git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894
      Referenceadded
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      https://git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8
      Referenceadded
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      https://git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c
      Referenceadded
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      https://git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d
      Referenceadded
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      https://git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34
      Referenceadded
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      https://git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b
      Referenceadded
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      https://git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6
      Referenceadded
      —
      https://git.kernel.org/stable/c/e2d19969c8d9198ecc3090bcd5312ecd503a3339

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

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