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.

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Source ID Title
Debian DLA Debian DLA DLA-4664-1 linux security update
Debian DLA Debian DLA DLA-4665-1 linux security update
Debian DLA Debian DLA DLA-4671-1 linux-6.1 security update
Debian DSA Debian DSA DSA-6355-1 linux security update
Ubuntu USN Ubuntu USN USN-8566-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8568-1 Linux kernel (OEM) vulnerabilities
Ubuntu USN Ubuntu USN USN-8569-1 Linux kernel (HWE) vulnerabilities
Ubuntu USN Ubuntu USN USN-8575-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8576-1 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-8593-1 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8575-2 Linux kernel vulnerabilities
Ubuntu USN Ubuntu USN USN-8576-2 Linux kernel (NVIDIA Tegra) vulnerabilities
Ubuntu USN Ubuntu USN USN-8597-1 Linux kernel (IBM) vulnerabilities
Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Sun, 14 Jun 2026 05:45:00 +0000

Type Values Removed Values Added
Metrics cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Tue, 09 Jun 2026 00:15:00 +0000

Type Values Removed Values Added
Weaknesses CWE-476
References
Metrics threat_severity

None

cvssV3_1

{'score': 7.0, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H'}

threat_severity

Moderate


Mon, 08 Jun 2026 15:45:00 +0000

Type Values Removed Values Added
Description 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.
Title Bluetooth: hci_uart: fix UAFs and race conditions in close and init paths
First Time appeared Linux
Linux linux Kernel
CPEs cpe:2.3:o:linux:linux_kernel:*:*:*:*:*:*:*:*
Vendors & Products Linux
Linux linux Kernel
References

Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: Linux

Published:

Updated: 2026-06-14T18:05:39.086Z

Reserved: 2026-05-13T15:03:33.109Z

Link: CVE-2026-46275

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-06-08T16:16:40.863

Modified: 2026-06-14T06:16:22.753

Link: CVE-2026-46275

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-06-08T00:00:00Z

Links: CVE-2026-46275 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-06-14T07:00:17Z

Weaknesses