mkpasswd in expect 5.2.8, as used by Red Hat Linux 6.2 through 7.0, seeds its random number generator with its process ID, which limits the space of possible seeds and makes it easier for attackers to conduct brute force password attacks.
https://exchange.xforce.ibmcloud.com/vulnerabilities/6382
http://www.securityfocus.com/bid/2632
http://www.kb.cert.org/vuls/id/527736
http://securitytracker.com/id?1001303
http://archives.neohapsis.com/archives/bugtraq/2001-04/0192.html
http://archives.neohapsis.com/archives/bugtraq/2001-04/0173.html