Heimdal is an implementation of Kerberos 5.
Przemyslaw Frasunek discovered several flaws in lukemftpd, which also apply to Heimdal ftpd's out-of-band signal handling code.
Additionally, a potential vulnerability that could lead to Denial of Service by the Key Distribution Center (KDC) has been fixed in this version.
A remote attacker could be able to run arbitrary code with escalated privileges, which can result in a total compromise of the server.
There is no known workaround at this time.
All Heimdal users should upgrade to the latest version:
# emerge sync
# emerge -pv ">=app-crypt/heimdal-0.6.3"
# emerge ">=app-crypt/heimdal-0.6.3"