CVE-2021-0129: 
NixOS vulnerability analysis and mitigation

CVE-2021-0129 is a vulnerability discovered in the Bluetooth subsystem (BlueZ) of the Linux kernel. The vulnerability involves improper access control in BlueZ that may allow an authenticated user to potentially enable information disclosure via adjacent access. This vulnerability was disclosed in 2021 and affects Linux kernel versions prior to 5.13 that support Intel BlueZ (Ubuntu Security, Debian Security).

The vulnerability stems from improper access control implementation during Bluetooth Passkey authentication method in Linux's BlueZ implementation. The issue specifically affects the Bluetooth pairing operation where permissions are not properly checked. This vulnerability has been assigned a CVSS v3.1 base score of 6.4 (Medium) with the vector CVSS:3.1/AV:A/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:N (NetApp Security).

When successfully exploited, this vulnerability could allow an attacker within range of two Bluetooth devices while they pair using Passkey authentication to obtain the shared secret (Passkey) and then impersonate either of the devices to each other. This could lead to disclosure of sensitive information or addition or modification of data (Debian LTS).

The vulnerability has been fixed in various Linux distributions through security updates. For Ubuntu, fixes were released for multiple versions including 21.04 (hirsute), 20.10 (groovy), 20.04 LTS (focal), and 18.04 LTS (bionic). For Debian, the fix was included in version 5.50-1.2~deb10u2 for the stable distribution (buster). Users are recommended to upgrade their bluez packages to the latest versions (Ubuntu Security, Debian Security).