The default configuration of the HP CM8060 Color MFP with Edgeline; Color LaserJet 3xxx, 4xxx, 5550, 9500, CMxxxx, CPxxxx, and Enterprise CPxxxx; Digital Sender 9200c and 9250c; LaserJet 4xxx, 5200, 90xx, Mxxxx, and Pxxxx; and LaserJet Enterprise 500 color M551, 600, M4555 MFP, and P3015 enables the Remote Firmware Update (RFU) setting, which allows remote attackers to execute arbitrary code by using a session on TCP port 9100 to upload a crafted firmware update.
https://lists.immunityinc.com/pipermail/dailydave/2011-November/000378.html
http://www.securitytracker.com/id?1026357
http://www.securityfocus.com/bid/51324
http://www.kb.cert.org/vuls/id/717921
http://secunia.com/advisories/47063
http://isc.sans.org/diary/Hacking+HP+Printers+for+Fun+and+Profit/12112
http://h20000.www2.hp.com/bizsupport/TechSupport/Document.jsp?objectID=c03102449