Linux Kernel up to 6.4.6 Bluetooth sco.c hci_conn_link null pointer dereference

Summaryinfo

A vulnerability was found in Linux Kernel up to 6.4.6. It has been declared as critical. Affected by this issue is the function hci_conn_link of the file sco.c of the component Bluetooth. Executing a manipulation can lead to null pointer dereference. This vulnerability appears as CVE-2023-54038. There is no available exploit. It is recommended to upgrade the affected component.

Detailsinfo

A vulnerability was found in Linux Kernel up to 6.4.6. It has been declared as critical. This vulnerability affects the function hci_conn_link of the file sco.c of the component Bluetooth. The manipulation with an unknown input leads to a null pointer dereference vulnerability. The CWE definition for the vulnerability is CWE-476. A NULL pointer dereference occurs when the application dereferences a pointer that it expects to be valid, but is NULL, typically causing a crash or exit. As an impact it is known to affect availability. CVE summarizes:

In the Linux kernel, the following vulnerability has been resolved: Bluetooth: hci_conn: return ERR_PTR instead of NULL when there is no link hci_connect_sco currently returns NULL when there is no link (i.e. when hci_conn_link() returns NULL). sco_connect() expects an ERR_PTR in case of any error (see line 266 in sco.c). Thus, hcon set as NULL passes through to sco_conn_add(), which tries to get hcon->hdev, resulting in dereferencing a NULL pointer as reported by syzkaller. The same issue exists for iso_connect_cis() calling hci_connect_cis(). Thus, make hci_connect_sco() and hci_connect_cis() return ERR_PTR instead of NULL.

The advisory is available at git.kernel.org. This vulnerability was named CVE-2023-54038 since 12/24/2025. Technical details are known, but there is no available exploit.

The vulnerability scanner Nessus provides a plugin with the ID 279980 (Linux Distros Unpatched Vulnerability : CVE-2023-54038), which helps to determine the existence of the flaw in a target environment.

Upgrading to version 6.4.7 eliminates this vulnerability. Applying the patch 357ab53c83a5322437fa434e9a9e3e0bafe6b383/b4066eb04bb67e7ff66e5aaab0db4a753f37eaad is able to eliminate this problem. The bugfix is ready for download at git.kernel.org. The best possible mitigation is suggested to be upgrading to the latest version.

The vulnerability is also documented in the databases at Tenable (279980) and CERT Bund (WID-SEC-2025-2920). If you want to get best quality of vulnerability data, you may have to visit VulDB.

Affected

• Open Source Linux Kernel

Productinfo

Type

• Operating System

Vendor

• Linux

Name

• Kernel

Version

• 6.4.0
• 6.4.1
• 6.4.2
• 6.4.3
• 6.4.4
• 6.4.5
• 6.4.6

License

• open-source

Website

• Vendor: https://www.kernel.org/

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If you want to get best quality of vulnerability data, you may have to visit VulDB.

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