CVE-2020-1751: 
NixOS vulnerability analysis and mitigation

An out-of-bounds write vulnerability was discovered in glibc before version 2.31 (CVE-2020-1751). The vulnerability specifically affects the backtrace function when handling signal trampolines on PowerPC systems. The issue was discovered in January 2020 and publicly disclosed in April 2020 (Sourceware Bug, NVD).

The vulnerability occurs when the backtrace function fails to properly check array bounds when storing frame addresses during signal trampoline handling on PowerPC systems. This vulnerability was introduced by commit d400dcac5e and was subsequently fixed in glibc 2.31. The issue has been assigned a CVSS v3.1 base score of 7.0 (HIGH) with the vector CVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:H (NVD).

The primary impact of this vulnerability is to system availability, with potential for denial of service or code execution. When successfully exploited, the vulnerability could lead to a complete loss of availability, integrity, and confidentiality on affected systems (NVD, NetApp Advisory).

The vulnerability requires local access and high attack complexity to exploit. An attacker would need low privileges but no user interaction to successfully exploit this vulnerability. The attack vector is limited to local access, making remote exploitation impossible (NVD).

The vulnerability was fixed in glibc version 2.31. Various Linux distributions have backported the fix to their supported versions. Ubuntu has released fixes in versions 2.30-0ubuntu2.2 for 19.10, 2.27-3ubuntu1.2 for 18.04 LTS, and 2.23-0ubuntu11.2 for 16.04 LTS (Ubuntu Notice, Gentoo Advisory).