mtink is a status monitor and inkjet cartridge changer for some Epson printers.
Tavis Ormandy from Gentoo Linux discovered that mtink uses insecure permissions on temporary files.
A local attacker could create symbolic links in the temporary files directory, pointing to a valid file somewhere on the filesystem. When mtink is executed, this would result in the file being overwritten with the rights of the user running the utility, which could be the root user.
There is no known workaround at this time.
All mtink users should upgrade to the latest version:
# emerge --sync
# emerge --ask --oneshot --verbose ">=net-print/mtink-1.0.5"