Unpatched libraries in Java and Python allows attacers to bypass firewall in remote networks. Vulnerability can be exploited for establishing another connection from server side. Server can be manipulated in such way that it connects to another server selected by the attacker and then run arbitrary commands. Among other posibilities this can be used to send e-mail using SMTP protocol. Affected libraries are sun.net.ftp.impl.FtpClient for Java and urllib and urllib2 for Python.