The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-10:07.mbuf.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-10:07.mbuf.asc

An mbuf is a basic unit of memory management in the FreeBSD kernel inter-process communication and networking subsystem. Network packets and socket buffers are dependent on mbufs for their storage. Data can be embedded directly in mbufs, or mbufs can instead reference external buffers. The sendfile(2) system call uses external mbuf storage to directly map the contents of a file into a chain of mbufs for transmission purposes. The mbuf object supports a read-only flag that must be honored to prevent modification or writes to buffer data in cases like these. The read-only flag is not correctly copied when a mbuf buffer reference is duplicated. When the sendfile(2) system call is used to transmit data over the loopback interface, this can result in the backing pages for the transmitted file being modified, causing data corruption.