umount, when running with the Linux 2.6.15 kernel on Slackware Linux 10.2, allows local users to trigger a NULL dereference and application crash by invoking the program with a pathname for a USB pen drive that was mounted and then physically removed, which might allow the users to obtain sensitive information, including core file contents.
http://www.securitytracker.com/id?1017729
http://www.securityfocus.com/bid/22850
http://www.mandriva.com/security/advisories?name=MDKSA-2007:053
http://archives.neohapsis.com/archives/fulldisclosure/2007-02/0012.html