The nfsrvd_readdir function in sys/fs/nfsserver/nfs_nfsdport.c in the new NFS server in FreeBSD 8.0 through 9.1-RELEASE-p3 does not verify that a READDIR request is for a directory node, which allows remote attackers to cause a denial of service (memory corruption) or possibly execute arbitrary code by specifying a plain file instead of a directory.