FreeBSD Security Advisory FreeBSD-SA-01:55 - The FreeBSD procfs can leak the memory of protected programs, including password hashes. The procfs code checks for gid kmem privilege when granting access to the /proc/<pid>/mem file - however, the code which is used to allow read-only access via the kmem group was incorrect, and inappropriately granted read access to the caller as long as they already had an open file descriptor for the procfs mem file. All released versions of FreeBSD 4.x including FreeBSD 4.3-RELEASE are vulnerable to this problem if the procfs filesystem is in use.