The NFS client implementation in the kernel in Red Hat Enterprise Linux (RHEL) 3 when a filesystem is mounted with the noacl option checks permissions for the open system call via vfs_permission (mode bits) data rather than an NFS ACCESS call to the server which allows local client processes to obtain a false success status from open calls that the server would deny and possibly obtain sensitive information about file permissions on the server as demonstrated in a root_squash environment. NOTE: it is uncertain whether any scenarios involving this issue cross privilege boundaries.