The cpansign verify functionality in the Module::Signature module before 0.72 for Perl allows attackers to bypass the signature check and execute arbitrary code via a SIGNATURE file with a "special unknown cipher" that references an untrusted module in Digest/.
https://bugzilla.redhat.com/show_bug.cgi?id=971096
http://www.ubuntu.com/usn/USN-1896-1
http://www.securityfocus.com/bid/60352
http://www.openwall.com/lists/oss-security/2013/06/05/16
http://lists.opensuse.org/opensuse-updates/2013-07/msg00043.html
http://lists.opensuse.org/opensuse-updates/2013-07/msg00039.html