CVE-2026-23146
Description
A flaw was found in the Linux kernel's Bluetooth HCI UART driver. A race condition exists where the hci_uart_write_work() function may attempt to access uninitialized private data if a TTY write wakeup occurs during the protocol initialization phase. This can lead to a NULL pointer dereference, potentially causing a system crash and resulting in a Denial of Service (DoS).
Mitigation
To mitigate this issue, prevent the `hci_uart` kernel module from loading. This can be achieved by creating a blacklist file for the module.
Create a file named `/etc/modprobe.d/blacklist-hci_uart.conf` with the following content:
blacklist hci_uart
install hci_uart /bin/true
After creating the file, regenerate the initramfs to ensure the blacklist is applied during boot:
For RHEL 9 and 10:
`sudo dracut -f -v`
For RHEL 6 ELS:
`sudo dracut -f`
A reboot is required for the changes to take effect. This mitigation will disable Bluetooth HCI UART functionality, which may impact systems relying on this driver for Bluetooth communication.
Common Vulnerability Scoring System (CVSS) Score Details
Info alert:Important note
CVSS scores for open source components depend on vendor-specific factors (e.g. version or build chain). Therefore, Red Hat's score and impact rating can be different from NVD and other vendors. Red Hat remains the authoritative CVE Naming Authority (CNA) source for its products and services (see Red Hat classifications).
CVSS v3 Score Breakdown
| Red Hat | NVD | cve.org | |
|---|---|---|---|
| Base Score | 5.3 | 5.5 | N/A |
| Attack Vector | Local | Local | N/A |
| Attack Complexity | High | Low | N/A |
| Privileges Required | Low | Low | N/A |
| User Interaction | None | None | N/A |
| Scope | Changed | Unchanged | N/A |
| Confidentiality | Low | None | N/A |
| Integrity Impact | Low | None | N/A |
| Availability Impact | Low | High | N/A |
Vector
Red Hat: CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:L
NVD: CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:H
Understanding the Weakness (CWE)
Availability
Technical Impact: DoS: Crash, Exit, or Restart
NULL pointer dereferences usually result in the failure of the process unless exception handling (on some platforms) is available and implemented. Even when exception handling is being used, it can still be very difficult to return the software to a safe state of operation.
Integrity,Confidentiality
Technical Impact: Execute Unauthorized Code or Commands; Read Memory; Modify Memory
In rare circumstances, when NULL is equivalent to the 0x0 memory address and privileged code can access it, then writing or reading memory is possible, which may lead to code execution.
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