This vulnerability allows remote attackers to execute arbitrary code on vulnerable installations of Sun Java Web Start. User interaction is required to exploit this vulnerability in that the target must visit a malicious page. The specific flaw exists in the useEncodingDecl() function used while checking xml based JNLP files for UTF8 characters. When a user downloads a malicious JNLP file, the data immediately preceding the opening of the xml tag is read into a static buffer. If an overly long key name in the xml header is included, a stack based buffer overflow occurs, resulting in an exploitable condition.