CVE-2023-53018 in Linux
Summary
by MITRE • 03/27/2025
In the Linux kernel, the following vulnerability has been resolved:
Bluetooth: hci_conn: Fix memory leaks
When hci_cmd_sync_queue() failed in hci_le_terminate_big() or hci_le_big_terminate(), the memory pointed by variable d is not freed, which will cause memory leak. Add release process to error path.
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Analysis
by VulDB Data Team • 12/07/2025
The vulnerability identified as CVE-2023-53018 represents a critical memory management flaw within the Linux kernel's Bluetooth subsystem, specifically affecting the HCI (Host Controller Interface) connection handling mechanisms. This issue resides in the bluetooth hci_conn module where improper memory deallocation occurs during error conditions, creating persistent memory leaks that can degrade system performance and potentially lead to resource exhaustion. The vulnerability manifests when the hci_cmd_sync_queue() function fails during execution of either hci_le_terminate_big() or hci_le_big_terminate() operations, leaving allocated memory structures unreleased and permanently tied to the system's memory pool. Such memory leaks directly contravene established security practices and can be exploited to exhaust available system resources, impacting overall system stability and performance.
The technical root cause of this vulnerability stems from inadequate error handling within the Bluetooth connection termination process, specifically in the LE BIG (Low Energy Broadcast Group) connection management functions. When hci_cmd_sync_queue() encounters an error condition during the termination sequence, the code path fails to execute proper memory cleanup routines for the variable d, which points to allocated memory structures containing connection metadata and associated resources. This represents a classic memory leak pattern categorized under CWE-401, specifically "Improper Release of Memory Before Removing Last Reference," where allocated memory is not properly deallocated before the program exits or returns to an error state. The flaw demonstrates a failure in implementing proper resource management protocols that should be enforced during all execution paths, particularly error conditions that are expected to occur during normal system operation.
The operational impact of CVE-2023-53018 extends beyond simple memory consumption issues, as persistent memory leaks can lead to system instability, reduced performance, and potential denial of service conditions. In environments where Bluetooth connections are frequently established and terminated, such as in mobile devices, IoT deployments, or industrial control systems, this vulnerability can accumulate over time to consume significant system resources. The memory leak affects the HCI connection management subsystem, which is fundamental to Bluetooth operations across Linux-based platforms, making this vulnerability particularly concerning for embedded systems and devices where memory resources are constrained. Attackers could potentially exploit this weakness by repeatedly triggering Bluetooth connection termination sequences to gradually consume system memory, leading to system crashes or service unavailability. This vulnerability aligns with ATT&CK technique T1499.004, "Resource Hijacking: Network Denial of Service," as it can contribute to resource exhaustion that impacts system availability.
The remediation for CVE-2023-53018 requires implementing proper memory cleanup routines in the error handling paths of the Bluetooth connection termination functions. The fix involves adding explicit release processes to the error path when hci_cmd_sync_queue() fails, ensuring that all allocated memory pointed to by variable d is properly freed regardless of execution outcome. This solution follows established secure coding practices and aligns with the principle of defensive programming where all allocated resources must be freed before function exit, particularly in error conditions. The fix demonstrates adherence to the principle of least privilege and resource management best practices, ensuring that system resources are properly managed throughout the entire lifecycle of Bluetooth connection operations. System administrators should prioritize applying this patch to all Linux systems running Bluetooth services, particularly those in production environments where continuous operation and resource availability are critical. The vulnerability underscores the importance of comprehensive error handling and memory management in kernel-level code, where improper resource cleanup can have cascading effects on system stability and security posture.