FreeBSD: VID-84ab03b6-6c20-11ed-b519-080027f5fec9 (CVE-2021-33621): rubygem-cgi -- HTTP response splitting vulnerability

Hiroshi Tokumaru reports: If an application that generates HTTP responses using the cgi gem with untrusted user input, an attacker can exploit it to inject a malicious HTTP response header and/or body. Also, the contents for a CGI::Cookie object were not checked properly. If an application creates a CGI::Cookie object based on user input, an attacker may exploit it to inject invalid attributes in Set-Cookie header. We think such applications are unlikely, but we have included a change to check arguments for CGI::Cookie#initialize preventatively.