DescriptionRubyGems 2.0.x before 2.0.17, 2.2.x before 2.2.5, and 2.4.x before 2.4.8 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 with a domain that is suffixed with the original domain name, aka a "DNS hijack attack." NOTE: this vulnerability exists because to an incomplete fix for CVE-2015-3900.
SourceCVE (at NVD; CERT, LWN, oss-sec, fulldisc, bugtraq, EDB, Metasploit, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, Mageia, GitHub code/issues, web search, more)
NVD severitymedium

Vulnerable and fixed packages

The table below lists information on source packages.

Source PackageReleaseVersionStatus
jruby (PTS)jessie1.5.6-9fixed
jessie (security)1.5.6-9+deb8u1fixed
stretch (security), stretch1.7.26-1+deb9u1fixed
buster, bullseye, sid9.1.17.0-3fixed
ruby2.1 (PTS)jessie2.1.5-2+deb8u3fixed
jessie (security)2.1.5-2+deb8u7fixed

The information below is based on the following data on fixed versions.

PackageTypeReleaseFixed VersionUrgencyOriginDebian Bugs
jrubysource(unstable)(not affected)
libgems-rubysource(unstable)(not affected)
ruby1.8source(unstable)(not affected)
ruby1.9.1source(unstable)(not affected)
ruby2.1source(unstable)(not affected)
ruby2.2source(unstable)(not affected)
rubygemssource(unstable)(not affected)


- rubygems <not-affected> (Affects versions between 2.0 and 2.4.6 and incomplete fix not applied)
- libgems-ruby <not-affected> (Affects versions between 2.0 and 2.4.6 and incomplete fix not applied)
- ruby1.8 <not-affected> (Vulnerable code not present)
- ruby1.9.1 <not-affected> (Bundles 1.8.23, vulnerable code introduced in later 1.9.1 versions; incomplete fix not applied)
- ruby2.1 <not-affected> (Incomplete fix not applied)
- ruby2.2 <not-affected> (Incomplete fix not applied)
- jruby <not-affected> (Incomplete fix not applied)
Original patch
introduced another vulnerability, assigned CVE-2015-4020. This CVE
only applies if only 6bbee35 was applied without 5c7bfb5

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