FreeBSD Security Advisory (FreeBSD-SA-04:08.heimdal.asc)

The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-04:08.heimdal.asc
Upgrade your system to the appropriate stable release or security branch dated after the correction date
Heimdal implements the Kerberos 5 network authentication protocols. Principals (i.e. users and services) represented in Kerberos are grouped into separate, autonomous realms. Unidirectional or bidirectional trust relationships may be established between realms to allow the principals in one realm to recognize the authenticity of principals in another. These trust relationships may be transitive. An authentication path is the ordered list of realms (and therefore KDCs) that were involved in the authentication process. The authentication path is recorded in Kerberos tickets as the `transited' field. It is possible for the Key Distribution Center (KDC) of a realm to forge part or all of the `transited' field. KDCs should validate this field before accepting authentication results, checking that each realm in the authentication path is trusted and that the path conforms to local policy. Applications are required to perform this type of checking if the KDC has not already done so. Prior to FreeBSD 5.1, Kerberos 5 was an optional component of FreeBSD, and was not installed by default. Some versions of Heimdal do not perform appropriate checking of the `transited' field.