FreeBSD Security Advisory FreeBSD-SA-01:30.ufs-ext2fs - A bug in the UFS filesystem allows users to obtain access to areas of the filesystem containing data from deleted files. The filesystem code is supposed to ensure that all filesystem blocks are zeroed before becoming available to user processes, but in a certain specific case this zeroing does not occur, and unzeroed blocks are passed to the user with their previous contents intact. Thus, if the block contains data which used to be part of a file or directory to which the user did not have access, the operation results in unauthorized access of data.