The remote upgrade capability in HP LaserJet 4200 and 4300 printers does not require a password, which allows remote attackers to upgrade firmware.
https://exchange.xforce.ibmcloud.com/vulnerabilities/17634
http://www.securityfocus.com/bid/11297
http://securitytracker.com/id?1011671
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=PSD_HPSBPI01085