The SecureRandom.random_bytes function in lib/securerandom.rb in Ruby before 1.8.7-p352 and 1.9.x before 1.9.2-p290 relies on PID values for initialization, which makes it easier for context-dependent attackers to predict the result string by leveraging knowledge of random strings obtained in an earlier process with the same PID.
lists.fedoraproject.org/pipermail/package-announce/2011-July/063062.html
lists.fedoraproject.org/pipermail/package-announce/2011-July/063071.html
redmine.ruby-lang.org/issues/4579
svn.ruby-lang.org/cgi-bin/viewvc.cgi?view=revision&revision=32050
svn.ruby-lang.org/repos/ruby/tags/v1_8_7_352/ChangeLog
svn.ruby-lang.org/repos/ruby/tags/v1_9_2_290/ChangeLog
www.openwall.com/lists/oss-security/2011/07/11/1
www.openwall.com/lists/oss-security/2011/07/12/14
www.openwall.com/lists/oss-security/2011/07/20/1
www.openwall.com/lists/oss-security/2011/07/20/16
www.redhat.com/support/errata/RHSA-2011-1581.html
www.ruby-lang.org/en/news/2011/07/02/ruby-1-8-7-p352-released/
www.ruby-lang.org/en/news/2011/07/15/ruby-1-9-2-p290-is-released/
www.securityfocus.com/bid/49015
bugzilla.redhat.com/show_bug.cgi?id=722415