The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-04:01.mksnap_ffs.asc

Upgrade your system to the appropriate stable release or security branch dated after the correction date https://secure1.securityspace.com/smysecure/catid.html?in=FreeBSD-SA-04:01.mksnap_ffs.asc

Mounted filesystems can have a variety of flags set on them. Some flags affect performance and reliability, while others enable or disable particular security-related features such as the ability to execute a binary stored on the filesystem or the use of access control lists to complement normal Unix file permissions. The mksnap_ffs(8) command creates a `snapshot' of a filesystem. A `snapshot' is a static representation of the state of the filesystem at a particular point in time. Snapshots have a variety of uses, but their primary purpose is to make it possible to run fsck(8) and dump(8) on live filesystems. The kernel interface for creating a snapshot of a filesystem is the same as that for changing the flags on that filesystem. Due to an oversight, the mksnap_ffs(8) command called that interface with only the snapshot flag set, causing all other flags to be reset to the default value.