Double free vulnerability in the ftpprchild function in ftppr in 3proxy 0.5 through 0.5.3i allows remote attackers to cause a denial of service (daemon crash) via multiple OPEN commands to the FTP proxy.
https://exchange.xforce.ibmcloud.com/vulnerabilities/37401
http://www.securityfocus.com/bid/26180
http://www.securityfocus.com/archive/1/482697/100/0/threaded
http://security.gentoo.org/glsa/glsa-200711-13.xml
http://secunia.com/advisories/27607
http://secunia.com/advisories/27353
http://lists.grok.org.uk/pipermail/full-disclosure/2007-October/066985.html