CVE-2023-53828: 
Linux Kernel vulnerability analysis and mitigation

CVE-2023-53828 is a use-after-free vulnerability in the Linux kernel's Bluetooth subsystem, specifically within the hci_sync component and the hci_add_adv_monitor() function. The flaw was publicly disclosed on December 9, 2025, and affects Linux kernel versions prior to the patched stable releases (6.1.53, 6.4.16, 6.5.3, and 6.6). The vulnerability was identified via KSAN (Kernel Sanitizer) reports and is classified as HIGH severity by Feedly's estimate, with an EPSS score of approximately 0.018% (Red Hat CVE, Feedly).

The root cause is a use-after-free (CWE-416) condition in the Linux kernel Bluetooth stack. During the advertisement monitor addition flow, hci_add_adv_monitor() calls msft_add_monitor_pattern(), which calls msft_add_monitor_sync(), which in an error path calls msft_le_monitor_advertisement_cb(), which in turn calls hci_free_adv_monitor() — freeing the *monitor object. After this deallocation, a bt_dev_dbg() call in hci_add_adv_monitor() still references monitor->handle, resulting in a use-after-free memory access. The fix replaces the freed pointer dereference with a local handle variable captured before the potential free (Red Hat CVE).

Exploitation of this use-after-free could lead to kernel memory corruption, potentially enabling a local attacker to cause a denial of service (kernel crash/panic) or, in more severe scenarios, escalate privileges on the affected system. The vulnerability is confined to systems with Bluetooth hardware and the MSFT Bluetooth extension enabled. Given the kernel-level nature of the bug, successful exploitation could compromise the integrity and availability of the entire system (Red Hat CVE).

The vulnerability is fixed in Linux kernel stable releases 6.1.53, 6.4.16, 6.5.3, and 6.6. Users should update their Linux kernel to one of these patched versions or a later release. The specific upstream commits addressing this issue are available in the kernel stable tree (commits 81d8e9f5, aafda69d, 8d66f7ce, and a2bcd2b6). As a temporary workaround where patching is not immediately possible, disabling Bluetooth or the MSFT Bluetooth extension can reduce exposure (Red Hat CVE).