Common Vulnerabilities and Exposures assigned an identifier CVE-2008-2841 to the following vulnerability: Argument injection vulnerability in XChat 2.8.7b and earlier on Windows, when Internet Explorer is used, allows remote attackers to execute arbitrary commands via the --command parameter in an ircs:// URI. Refences: http://www.milw0rm.com/exploits/5795 http://forum.xchat.org/viewtopic.php?t=4218 http://secunia.com/advisories/30695
This seems to be IE flaw rather than xchat flaw, as this can be used to inject additional command line arguments to any external protocol handler application. Firefox does have a irc:// protocol handler, but seems to escape / URL-encode arguments passed to external program properly (as any sane browse should do). Additionally, --command argument to xchat was only introduced recently. It is only supported in 2.8.6 currently only in Rawhide. Versions of xchat in Fedora 8 and 9, and Red Hat Enterprise Linux 2.1, 3, 4 and 5 do not support --command command line argument.
Window$-only exploit, does not affect any version of Fedora or RHEL.