The Mail gem before 2.4.3 for Ruby allows remote attackers to execute arbitrary commands via shell metacharacters in a (1) sendmail or (2) exim delivery.
https://github.com/mikel/mail/blob/9beb079c70d236a5ad2e1ba95b2c977e55deb7af/CHANGELOG.rdoc
https://bugzilla.redhat.com/show_bug.cgi?id=816352
https://bugzilla.novell.com/show_bug.cgi?id=759092
http://www.openwall.com/lists/oss-security/2012/04/26/1
http://www.openwall.com/lists/oss-security/2012/04/25/8
http://secunia.com/advisories/48970
http://lists.fedoraproject.org/pipermail/package-announce/2012-May/080747.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-May/080648.html
http://lists.fedoraproject.org/pipermail/package-announce/2012-May/080645.html