HighCVE-2026-31500

    Linux Kernel: Use-After-Free (CVE-2026-31500)

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

    What is affected, what to do

    In the Linux kernel, the following vulnerability has been resolved: Bluetooth: btintel: serialize btintel_hw_error() with hci_req_sync_lock btintel_hw_error() issues two __hci_cmd_sync() calls (HCI_OP_RESET and Intel exception-info retrieval) without holding hci_req_sync_lock(). This lets it race against hci_dev_do_close() -> btintel_shutdown_combined(), which also runs __hci_cmd_sync() under the same lock.

    Update Linux Kernel to version 6.1.175, Linux Kernel to version 6.6.131, Linux Kernel to version 6.12.80.

    Affected
    • Linux Kernel lt 4.3..6.1.175
    • Linux Kernel lt 6.2..6.6.131
    • Linux Kernel lt 6.7..6.12.80
    • Linux Kernel lt 6.13..6.18.21
    • Linux Kernel lt 6.19..6.19.11
    • Linux Kernel lt 6.20..7.0
    Fixed in
    • Linux Kernel 6.1.175
    • Linux Kernel 6.6.131
    • Linux Kernel 6.12.80
    • Linux Kernel 6.18.21
    • Linux Kernel 6.19.11
    • Linux Kernel 7.0

    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: NVD, CVSS v3

    7.8

    CVSS v3

    Severity High on the scale from 0 to 10.

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

    0.1 %

    EPSS score

    Low — model estimates < 1% exploitation likelihood.

    Source: FIRST EPSS, percentile 2.2

    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
    55.57 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
    2.2
    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
    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: Bluetooth: btintel: serialize btintel_hw_error() with hci_req_sync_lock btintel_hw_error() issues two __hci_cmd_sync() calls (HCI_OP_RESET and Intel exception-info retrieval) without holding hci_req_sync_lock(). This lets it race against hci_dev_do_close() -> btintel_shutdown_combined(), which also runs __hci_cmd_sync() under the same lock. When both paths manipulate hdev->req_status/req_rsp concurrently, the close path may free the response skb first, and the still-running hw_error path hits a slab-use-after-free in kfree_skb(). Wrap the whole recovery sequence in hci_req_sync_lock/unlock so it is serialized with every other synchronous HCI command issuer. Below is the data race report and the kasan report: BUG: data-race in __hci_cmd_sync_sk / btintel_shutdown_combined read of hdev->req_rsp at net/bluetooth/hci_sync.c:199 by task kworker/u17:1/83: __hci_cmd_sync_sk+0x12f2/0x1c30 net/bluetooth/hci_sync.c:200 __hci_cmd_sync+0x55/0x80 net/bluetooth/hci_sync.c:223 btintel_hw_error+0x114/0x670 drivers/bluetooth/btintel.c:254 hci_error_reset+0x348/0xa30 net/bluetooth/hci_core.c:1030 write/free by task ioctl/22580: btintel_shutdown_combined+0xd0/0x360 drivers/bluetooth/btintel.c:3648 hci_dev_close_sync+0x9ae/0x2c10 net/bluetooth/hci_sync.c:5246 hci_dev_do_close+0x232/0x460 net/bluetooth/hci_core.c:526 BUG: KASAN: slab-use-after-free in sk_skb_reason_drop+0x43/0x380 net/core/skbuff.c:1202 Read of size 4 at addr ffff888144a738dc by task kworker/u17:1/83: __hci_cmd_sync_sk+0x12f2/0x1c30 net/bluetooth/hci_sync.c:200 __hci_cmd_sync+0x55/0x80 net/bluetooth/hci_sync.c:223 btintel_hw_error+0x186/0x670 drivers/bluetooth/btintel.c:260

    Source: suse_csaf, Debian Security Advisories, Debian LTS Advisories, siemens_advisory, Ubuntu Security Notices, BSI WID Portal, BSI CSAF, cvelistv5, NVD (NIST), Microsoft Security Update Guide, ENISA EUVD, 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
    • 6.2 – < 6.6.131
    • 4.3 – < 6.1.175
    • 6.7 – < 6.12.80
    • 6.19 – < 6.19.11
    • 6.13 – < 6.18.21
    • 6.20 – < 7.0
    • 6.6.131
    • 6.1.175
    • 6.12.80
    • 6.19.11
    • 6.18.21
    • 7.0
    SiemensSIMATIC S7
    • 1500 TM MFP V1.1.1 GNU/Linux subsystem
    • —

    Vendors and products

    Affected operating systems

    Affected operating systems
    Linuxdebianlinuxbookworm
    Linuxdebianlinuxtrixie
    Linuxdebianlinux-6.1bullseye
    Linuxlinuxlinux_kernel4.3
    Linuxlinuxlinux_kernel7.0
    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 modifiedLinux

      Show 17 original changes
      Individual changes of this event as published by NVD
      TypeActionBeforeAfter
      Referenceadded
      —
      https://git.kernel.org/stable/c/5f84e845648dfa86e42de5487f1a774b42f0444d
      Referenceadded
      —
      https://git.kernel.org/stable/c/66696648af477dc87859e5e4b607112f5f29d010
      Referenceadded
      —
      https://git.kernel.org/stable/c/7e041d0aad1d4d43d921ace052e04f4e2cacaed3
      Referenceadded
      —
      https://git.kernel.org/stable/c/94d8e6fe5d0818e9300e514e095a200bd5ff93ae
      Referenceadded
      —
      https://git.kernel.org/stable/c/e10a4cb72468686ffbe8bb2b0520e37f6be1a0c5
      Referenceadded
      —
      https://git.kernel.org/stable/c/f7d84737663ad4a120d2d8ef1561a4df91282c2e
      Referenceremoved
      https://git.kernel.org/stable/c/5f84e845648dfa86e42de5487f1a774b42f0444d
      —
      Referenceremoved
      https://git.kernel.org/stable/c/66696648af477dc87859e5e4b607112f5f29d010
      —
      Referenceremoved
      https://git.kernel.org/stable/c/7e041d0aad1d4d43d921ace052e04f4e2cacaed3
      —
      Referenceremoved
      https://git.kernel.org/stable/c/94d8e6fe5d0818e9300e514e095a200bd5ff93ae
      —
      Referenceremoved
      https://git.kernel.org/stable/c/e10a4cb72468686ffbe8bb2b0520e37f6be1a0c5
      —
      Referenceremoved
      https://git.kernel.org/stable/c/f7d84737663ad4a120d2d8ef1561a4df91282c2e
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/5f84e845648dfa86e42de5487f1a774b42f0444d Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/66696648af477dc87859e5e4b607112f5f29d010 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/94d8e6fe5d0818e9300e514e095a200bd5ff93ae Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/e10a4cb72468686ffbe8bb2b0520e37f6be1a0c5 Types: Patch
      —
      Reference typeremoved
      https://git.kernel.org/stable/c/f7d84737663ad4a120d2d8ef1561a4df91282c2e Types: Patch
      —

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

    2. 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/2026/31xxx/CVE-2026-31500.json">CVE-2026-31500</a>
      Referenceadded
      —
      https://cert-portal.siemens.com/productcert/html/ssa-784472.html

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

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