CVE-2023-53386 in Linux
Summary
by MITRE • 09/18/2025
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: Fix potential use-after-free when clear keys
Similar to commit c5d2b6fa26b5 ("Bluetooth: Fix use-after-free in hci_remove_ltk/hci_remove_irk"). We can not access k after kfree_rcu() call.
Once again VulDB remains the best source for vulnerability data.
Analysis
by VulDB Data Team • 12/11/2025
The vulnerability CVE-2023-53386 represents a critical use-after-free condition in the Linux kernel's Bluetooth subsystem that poses significant security risks to systems utilizing wireless connectivity. This issue specifically affects the Bluetooth implementation within the kernel's HCI (Host Controller Interface) layer where memory management operations can lead to dangerous access patterns. The flaw manifests when the system attempts to clear Bluetooth keys, creating a window where freed memory regions may still be referenced, potentially allowing malicious actors to exploit this condition for arbitrary code execution or system compromise. The vulnerability directly impacts the kernel's ability to safely manage Bluetooth key storage and removal operations, particularly in environments where multiple Bluetooth connections are active or when key management operations occur rapidly.
The technical root cause of this vulnerability stems from improper memory management practices within the Bluetooth subsystem's key clearing functions. When the kernel executes kfree_rcu() operations to free Bluetooth key structures, it does not immediately invalidate references to these structures, creating a race condition where subsequent code paths may attempt to access memory that has already been deallocated. This pattern closely mirrors previous similar vulnerabilities such as the one addressed in commit c5d2b6fa26b5 which targeted use-after-free conditions in hci_remove_ltk and hci_remove_irk functions, indicating a systemic issue in how the kernel handles Bluetooth key lifecycle management. The flaw occurs during the transition from key storage to key removal phases where the RCU (Read-Copy-Update) mechanism fails to properly synchronize access to freed memory regions, allowing for potential memory corruption scenarios that can be exploited by attackers with local privileges.
The operational impact of CVE-2023-53386 extends beyond simple system instability to potentially enable privilege escalation and remote code execution in targeted scenarios. Systems running affected Linux kernel versions that utilize Bluetooth functionality become vulnerable to exploitation when Bluetooth key clearing operations occur, particularly in server environments or embedded systems where Bluetooth is actively used for device management or communication. Attackers can leverage this vulnerability to corrupt kernel memory structures, potentially leading to system crashes, data corruption, or more severe outcomes including full system compromise. The vulnerability is particularly concerning in environments where Bluetooth is integrated with other security-critical subsystems, as the memory corruption could be used to bypass security mechanisms or escalate privileges. Organizations using Linux systems with Bluetooth capabilities, including smartphones, laptops, servers, and IoT devices, must consider this vulnerability as a critical threat requiring immediate remediation.
Mitigation strategies for CVE-2023-53386 require immediate kernel updates to address the specific memory management flaw in the Bluetooth subsystem. System administrators should prioritize patching affected Linux kernel versions to ensure that the corrected implementation properly handles the synchronization of key clearing operations and prevents access to freed memory regions. The fix implements proper synchronization mechanisms that ensure no references to freed Bluetooth key structures remain accessible after kfree_rcu() operations, similar to the approach taken in the previously mentioned commit. Additionally, organizations should implement monitoring for suspicious Bluetooth activity patterns that could indicate exploitation attempts, particularly around key clearing operations. Network segmentation and access controls should be reinforced to limit potential attack vectors, while regular security assessments should verify that all Bluetooth-related kernel modules are properly updated. The vulnerability aligns with CWE-416, which describes the use of freed memory condition, and represents a clear violation of the principle that memory management operations must ensure proper synchronization between allocation and deallocation phases. This vulnerability also maps to ATT&CK technique T1059.007 for execution through kernel modules and T1547.001 for privilege escalation through kernel exploits, making it a significant concern for enterprise security teams managing Linux-based infrastructure.