votes.cgi in Bugzilla 2.16.3 and earlier, and 2.17.1 through 2.17.4, allows remote attackers to read a user's voting page when that user has voted on a restricted bug, which allows remote attackers to read potentially sensitive voting information by modifying the who parameter.
https://exchange.xforce.ibmcloud.com/vulnerabilities/13600
http://www.securityfocus.com/bid/8953
http://www.securityfocus.com/archive/1/343185
http://distro.conectiva.com.br/atualizacoes/?id=a&anuncio=000774