MySQL is a popular multi-threaded, multi-user SQL server.
Jean-David Maillefer discovered a format string vulnerability in time.cc where MySQL fails to properly handle specially formatted user input to the date_format function.
By specifying a format string as the first parameter to the date_format function, an authenticated attacker could cause MySQL to crash, resulting in a Denial of Service.
There is no known workaround at this time.
All MySQL users should upgrade to the latest version:
# emerge --sync # emerge --ask --verbose --oneshot ">=dev-db/mysql-4.1.21"