Advisory: Long hostnames in file: URLs can cause execution of arbitrary code
Exceptionally long host names in file: URLs can cause a buffer overflow, which may be exploited to execute arbitrary code. Remote Web pages cannot refer to file: URLs, so successful exploitation involves tricking users into manually opening the exploit URL, or a local file that refers to it.
Opera Software has released Opera 9.63, where this issue has been fixed.
Thanks to Vitaly McLain for reporting this issue to Opera Software.