Postfix is a mail server and an alternative to the widely-used Sendmail program.
By default, Berkeley DB reads a DB_CONFIG configuration file from the current working directory. This is an undocumented behavior.
A local attacker, by using a specially crafted DG_CONFIG file, could possibly escalate privileges to the root group.
There is no known workaround at this time.
All Postfix users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=mail-mta/postfix-3.1.6"