CVE-2021-26675: 
NixOS vulnerability analysis and mitigation

CVE-2021-26675 is a stack-based buffer overflow vulnerability discovered in the dnsproxy component of ConnMan versions before 1.39. The vulnerability was initially reported by Tesla researchers to SUSE and ConnMan upstream maintainers, and was publicly disclosed in February 2021. This security flaw affects ConnMan, a lightweight network manager used in Tesla automobiles and other automotive infotainment systems (TBONE, OSS Security).

The vulnerability is a stack-based buffer overflow in the dnsproxy component that could be exploited by network-adjacent attackers to execute arbitrary code. The issue has been assigned a CVSS v3.1 base score of 8.8 (HIGH) with the vector string CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H, indicating adjacent network access, low attack complexity, no privileges required, and no user interaction needed (NVD).

If successfully exploited, this vulnerability could allow attackers to execute arbitrary code on affected systems. In Tesla vehicles specifically, attackers could potentially unlock doors and trunk, change seat positions, and modify steering and acceleration modes - essentially controlling functions accessible through the infotainment system console. However, the exploit does not provide direct drive control of the vehicle (TBONE).

The vulnerability is considered highly exploitable as it requires no user interaction and can be triggered by network-adjacent attackers. Security researchers demonstrated that the vulnerability could be exploited without physical access to Tesla vehicles, using only emulation tools. The researchers noted that the vulnerability was potentially 'wormable' and could have been weaponized to affect multiple vehicles in proximity (TBONE).

The vulnerability was patched in ConnMan version 1.39, released in February 2021. Tesla addressed the issue in their update 2020.44 released in late October 2020. Various Linux distributions have also released security updates: Debian released fixes in version 1.36-2.1~deb10u1 for Buster and 1.33-3+deb9u2 for Stretch, Ubuntu patched versions for 18.04 LTS and 20.04 LTS, and Gentoo fixed the issue in version 1.40 (Debian Security, Ubuntu Security, Gentoo Security).

The vulnerability discovery highlighted significant security concerns in automotive software components. The researchers responsibly disclosed the vulnerability to Tesla first, followed by engaging the German CERT to inform the wider automotive industry in January 2021. The researchers specifically chose not to weaponize the exploit into a worm, despite its potential for such abuse (TBONE).