CVE-2023-40283 in Linux
Summary
by MITRE • 08/14/2023
An issue was discovered in l2cap_sock_release in net/bluetooth/l2cap_sock.c in the Linux kernel before 6.4.10. There is a use-after-free because the children of an sk are mishandled.
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Analysis
by VulDB Data Team • 02/26/2026
The vulnerability identified as CVE-2023-40283 represents a critical use-after-free condition within the Linux kernel's Bluetooth implementation, specifically affecting the l2cap_sock_release function in net/bluetooth/l2cap_sock.c. This flaw exists in kernel versions prior to 6.4.10 and demonstrates a fundamental memory management error that can lead to arbitrary code execution. The issue occurs when handling socket children during the release process, creating a scenario where freed memory regions are still accessed by child socket objects, thereby enabling potential exploitation by malicious actors.
The technical root cause of this vulnerability stems from improper handling of socket child relationships during the cleanup phase of Bluetooth L2CAP (Logical Link Control and Adaptation Protocol) socket operations. When l2cap_sock_release is invoked to terminate a socket connection, the function fails to properly account for child socket objects that may reference the parent socket's memory space. This mismanagement creates a window where child sockets can continue to reference memory that has already been freed, leading to unpredictable behavior and potential privilege escalation. The vulnerability manifests as a classic use-after-free condition, which falls under CWE-416, specifically categorized as the reuse of freed memory.
From an operational standpoint, this vulnerability presents significant security implications for systems running affected Linux kernel versions, particularly those with Bluetooth functionality enabled. Attackers can exploit this condition by establishing specific Bluetooth connections and manipulating socket relationships to trigger the use-after-free scenario. The resulting memory corruption can be leveraged to execute arbitrary code with kernel-level privileges, effectively compromising the entire system. This type of vulnerability aligns with ATT&CK technique T1068, which involves exploiting local privileges to gain elevated access, and T1547, which covers the persistence mechanisms that can be established through kernel-level exploits.
The impact of CVE-2023-40283 extends beyond simple privilege escalation, as it represents a fundamental flaw in the kernel's memory management subsystem that could be exploited across multiple attack vectors. Systems with Bluetooth capabilities, including servers, desktops, and mobile devices running Linux, are at risk if they have not been updated to kernel version 6.4.10 or later. The vulnerability's exploitation potential makes it particularly dangerous in environments where Bluetooth is actively used, such as industrial control systems, automotive applications, or any infrastructure requiring wireless communication protocols. Organizations should prioritize patching and implement additional monitoring measures to detect potential exploitation attempts, as the use-after-free condition can be challenging to detect through conventional security scanning methods. The fix implemented in kernel version 6.4.10 addresses the core memory management issue by ensuring proper synchronization and cleanup of child socket references during the release process, thereby preventing the access to freed memory regions that previously enabled exploitation.