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This bulletin was written by Vigil@nce : http://vigilance.fr/

SYNTHESIS OF THE VULNERABILITY

A local attacker can use FUSE and a symbolic link, in order to

unmount a file system.

Severity: 1/4

Creation date: 05/11/2010

DESCRIPTION OF THE VULNERABILITY

The FUSE (Filesystem in USErspace) feature can be used by an
application to generate a virtual file system. For example:

./fuse_application /mount_point &
[using the mount point]
fusermount -u /mount_point

The fusermount command unmounts the mount point.

However, during fusermount execution, if the mounted path is
replaced by a link, the mount point pointed by the symlink can be
unmounted by the user.

A local attacker can therefore use FUSE and a symbolic link, in
order to unmount a file system.

ACCESS TO THE COMPLETE VIGIL@NCE BULLETIN

http://vigilance.fr/vulnerability/FUSE-unmounting-file-systems-10104