CVE-2023-53673: 
Linux Kernel vulnerability analysis and mitigation

A use-after-free vulnerability was discovered in the Linux kernel's Bluetooth implementation, specifically in the handling of HCI (Host Controller Interface) disconnect events. The vulnerability was identified on October 7, 2025, and affects the Bluetooth subsystem in the Linux kernel (NVD, RedHat).

The vulnerability occurs in the hci_cs_disconnect function where hci_conn_del is called even if disconnection fails. ISO, L2CAP, and SCO connections reference the hci_conn without proper reference counting through hci_conn_get, leading to a use-after-free condition when disconn_cfm is not called before cleanup. The issue has been assigned a CVSS v3.1 base score of 7.0, indicating high severity (RedHat).

The vulnerability can lead to use-after-free conditions in the kernel's Bluetooth subsystem, potentially resulting in system crashes, memory corruption, or possible code execution. This affects systems utilizing Bluetooth functionality, particularly those handling ISO, L2CAP, and SCO connections (RedHat).

The vulnerability has been resolved in the Linux kernel through a patch that ensures the disconnect callback is called before deleting the connection. Affected systems should be updated to the patched version. Red Hat Enterprise Linux 8 and 9 users should apply the available security updates (RedHat).