The FreeBSD Security Team has identified a little bug in FreeBSD with speudofs:
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.
II. Problem Description
The pfs_getextattr(9) function, used by pseudofs for handling extended attributes, attempts to unlock a mutex which was not previously locked.
To find out more about the impact, a work-around and solution, check out the advisory page: