CVE-2020-18442: 
NixOS vulnerability analysis and mitigation

CVE-2020-18442 is a vulnerability discovered in zziplib version 0.13.69, a lightweight library designed for extracting data from zip files. The vulnerability was identified as an infinite loop issue that could lead to denial of service attacks (NVD, Debian Security).

The vulnerability stems from incorrect handling of the return value of the 'zzip_file_read' function in the 'unzzip_cat_file' function. When zzip_file_read returns -1 indicating an error, the caller function unzzip_cat_file fails to properly handle this return value, resulting in an infinite loop condition. The vulnerability has been assigned a CVSS v3.1 base score of 3.3 (LOW) with the vector string CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L (NVD).

When exploited, this vulnerability allows remote attackers to cause a denial of service condition through an infinite loop triggered by manipulating the return value of the zzip_file_read function (GitHub Issue).

The vulnerability requires local access and low privileges to exploit. The attack complexity is low, and no user interaction is required for exploitation (NVD).

The vulnerability has been fixed in multiple distributions. Debian 9 (Stretch) released version 0.13.62-3.2~deb9u2, Fedora 34 and 35 released version 0.13.72-1 to address this issue. Users are recommended to upgrade to the latest available version of zziplib (Debian LTS, Fedora Update).