RubyGems 2.0.x before 2.0.16, 2.2.x before 2.2.4, and 2.4.x before 2.4.7 does not validate the hostname when fetching gems or making API requests, which allows remote attackers to redirect requests to arbitrary domains via a crafted DNS SRV record, aka a “DNS hijack attack.”
blog.rubygems.org/2015/05/14/CVE-2015-3900.html
lists.fedoraproject.org/pipermail/package-announce/2015-August/163502.html
lists.fedoraproject.org/pipermail/package-announce/2015-August/163600.html
lists.fedoraproject.org/pipermail/package-announce/2015-August/164236.html
rhn.redhat.com/errata/RHSA-2015-1657.html
www.openwall.com/lists/oss-security/2015/06/26/2
www.oracle.com/technetwork/topics/security/bulletinoct2015-2511968.html
www.securityfocus.com/bid/75482
puppet.com/security/cve/CVE-2015-3900
www.trustwave.com/Resources/Security-Advisories/Advisories/TWSL2015-007/?fid=6356
www.trustwave.com/Resources/SpiderLabs-Blog/Attacking-Ruby-Gem-Security-with-CVE-2015-3900/