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PatchSiren cyber security CVE debrief

CVE-2026-46275 Linux CVE debrief

CVE-2026-46275 is a HIGH severity vulnerability in the Linux kernel Bluetooth HCI UART implementation. The vulnerability allows for Use-After-Free (UAF) and Null Pointer Dereference (NPD) conditions due to improper lifecycle management of hci_uart. The primary issue arises from the workqueues (init_ready and write_work) only being 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.

Vendor
Linux
Product
Unknown
CVSS
HIGH 7.8
CISA KEV
Not listed in stored evidence
Original CVE published
2026-06-08
Original CVE updated
2026-07-23
Advisory published
2026-06-08
Advisory updated
2026-07-23

Who should care

Linux kernel developers and maintainers, Bluetooth HCI UART implementation users

Technical summary

The vulnerability is caused by improper synchronization and lifecycle management of hci_uart. The fixes involve re-ordering hci_uart_tty_close() to clear HCI_UART_PROTO_READY first, followed by a cancel_work_sync(&hu->write_work), relocating hu->proto->close(hu) strictly prior to hci_free_dev(hdev), and moving the hdev->stat.byte_rx increment in hci_uart_tty_receive() inside the proto_lock read-side critical section.

Defensive priority

high

Recommended defensive actions

  • Apply the patches provided by the Linux kernel maintainers to fix the vulnerability.
  • Ensure that the HCI_UART_PROTO_READY flag is set during TTY close to prevent UAF and NPD conditions.
  • Use the official CVE record [cve-org] and NVD detail [nvd] for further information.

Evidence notes

The vulnerability has a CVSS score of 7.8 and is classified as HIGH severity. The CVE record [cve-org] and NVD detail [nvd] provide further information on the vulnerability.

Sources and references

Verified primary and authoritative sources

  • CVE-2026-46275 CVE Program record

    Publisher, destination, and source semantics verified

    URL: https://www.cve.org/CVERecord?id=CVE-2026-46275

    CVE Program - Official CVE Program record with source-provided CVE metadata.

  • CVE-2026-46275 NVD vulnerability detail

    Publisher, destination, and source semantics verified

    URL: https://nvd.nist.gov/vuln/detail/CVE-2026-46275

    NIST National Vulnerability Database - Official NIST NVD detail page and source-specific vulnerability assessment.

Supplemental references

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/192cb0f1ca706d9a1bc36ae0ad5f666d1e4fd894

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/7338031946bd06f6dff149e67b60c4cd083bfea8

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/78aad93e938f013d9272fe0ee168f27883afa95c

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/81c7a3c22a0f2808cf4ae0b4908f59763b23606d

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/9d20d48be2c4a071fb015eb09bda2cecd25daf34

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/c1bb9336ae6b54a5f6a353c4bd4ed9a4307e429b

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

  • Source reference

    Unverified legacy reference

    URL: https://git.kernel.org/stable/c/c85cff648a2bc92322912db5f1727ad05afae7b6

    416baaa9-dc9f-4396-8d5f-8c081fb06d67

Methodology and review provenance

AI-assisted synthesis based on stored public vulnerability evidence. System validation, approval state, and publication status do not by themselves establish human review of this revision. PatchSiren helps prioritize defensive review and does not prove exposure or remediation on any system.