The remote host is missing an update to the system as announced in the referenced advisory FreeBSD-SA-10:09.pseudofs.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-10:09.pseudofs.asc

pseudofs offers an abstract API for pseudo file systems which is utilized by procfs(5) and linprocfs(5). It provides generic file system services such as ACLs, extended attributes which interface with VFS and which are otherwise onerous to implement. This enables pseudo file system authors to add this functionality to their file systems with minimal effort. The pfs_getextattr(9) function, used by pseudofs for handling extended attributes, attempts to unlock a mutex which was not previously locked.