Critical Bluetooth Vulnerability in Linux Kernel: Div-by-Zero and Integer Overflow
Summary
CVE-2024-36968: In the Linux kernel, the following vulnerability has been resolved: Bluetooth: L2CAP: Fix div-by-zero in l2cap_le_flowctl_init() l2cap_le_flowctl_init() can cause both div-by-zero and an integer overflow since hdev->le_m... Affects linux versions 5.10.103-1 – 6.9.9-1. No fix is published. How to fix ↓
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Background
The Linux kernel is the core component of many operating systems, providing essential services for all other parts of the system. It manages hardware resources, system calls, and security features. The kernel's Bluetooth subsystem facilitates wireless communication between devices. This vulnerability affects the L2CAP (Logical Link Control and Adaptation Protocol) layer, which is crucial for Bluetooth communication, making it a significant concern for users relying on Bluetooth functionalities.
Vulnerability Detail
In the Linux kernel, a vulnerability has been identified in the Bluetooth L2CAP layer, specifically within the function l2cap_le_flowctl_init(). This issue can lead to both a division by zero and an integer overflow due to the improper validation of the hdev->le_mtu value. If the MTU (Maximum Transmission Unit) does not fall within a valid range, it can cause the system to crash or behave unpredictably. The vulnerability arises from the lack of early validation checks during the connection process, which could potentially allow an attacker to exploit this flaw, leading to denial of service or other malicious outcomes.
How To Fix
No fixed version is published for this vulnerability.
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Workaround
As a temporary workaround, users can disable Bluetooth functionality until the kernel is updated. This can be done by executing the following command in the terminal:
sudo systemctl stop bluetooth.service
However, this is not a permanent solution and users should prioritize updating their kernel as soon as possible.
Conclusion
The vulnerability CVE-2024-36968 in the Linux kernel's Bluetooth subsystem poses significant risks due to potential division by zero and integer overflow errors. Users are strongly encouraged to update their systems to the latest kernel version to mitigate these risks and ensure secure Bluetooth communications.
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FAQ
The CVSS score of this vulnerability is 6.5, indicating a medium severity level.
You can use Vulert, which monitors and alerts for open-source vulnerabilities in real-time. You can check if your application is affected by this vulnerability using the Vulert playground without any signup at Vulert Scanner.
Exploiting this vulnerability could lead to a denial of service, causing the system to crash or become unresponsive when Bluetooth connections are attempted.
Yes, users should upgrade to the latest version of the Linux kernel where this vulnerability has been patched. For Debian 13, the fixed version is 6.8.11-1.
If an immediate update is not possible, it is advisable to disable Bluetooth functionality as a temporary measure to mitigate the risk.
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