In Gentoo Portage before 3.0.47, there is missing PGP validation of executed code: the standalone emerge-webrsync downloads a .gpgsig file but does not perform signature verification. Unless emerge-webrsync is used, Portage is not vulnerable.
{ "versions": [ { "introduced": "0" }, { "fixed": "3.0.47" } ] }
"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2016-20021.json"