The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-07:05.libarchive.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-07:05.libarchive.asc

The libarchive library provides a flexible interface for reading and writing streaming archive files such as tar and cpio, and has been the basis for FreeBSD's implementation of the tar(1) utility since FreeBSD 5.3. Several problems have been found in the code used to parse the tar and pax interchange formats. These include entering an infinite loop if an archive prematurely ends within a pax extension header or if certain types of corruption occur in pax extension headers [CVE-2007-3644] dereferencing a NULL pointer if an archive prematurely ends within a tar header immediately following a pax extension header or if certain other types of corruption occur in pax extension headers [CVE-2007-3645] and miscomputing the length of a buffer resulting in a buffer overflow if yet another type of corruption occurs in a pax extension header [CVE-2007-3641].