HTTP File Server (HFS) before 2.2c allows remote attackers to append arbitrary text to the log file by using the base64 representation of this text during HTTP Basic Authentication.
https://exchange.xforce.ibmcloud.com/vulnerabilities/39876
http://www.syhunt.com/advisories/hfshack.txt
http://www.syhunt.com/advisories/hfs-1-username.txt
http://www.securityfocus.com/bid/27423
http://www.securityfocus.com/archive/1/486874/100/0/threaded