FUSE: incorrect filtering of environment variables leading to privilege escalation

FUSE: incorrect filtering of environment variables leading to privilege escalation The fusermount binary in FUSE does not properly clear the environment before invoking mount or umount as root that allows a local user to overwrite arbitrary files. fuse March 09, 2016 March 09, 2016: 1 550152 local 2.9.4 2.9.4

FUSE provides an interface for filesystems implemented in userspace.

The fusermount binary calls setuid(geteuid()) to reset the RUID when it invokes /bin/mount so that it can use privileged mount options that are normally restricted if RUID != EUID. FUSE does not properly clear environment variables before invoking mount or umount as root allowing this to be passed to operations using elevated privileges such as LIBMOUNT_MTAB that is used by the mount commands debugging feature.

The FUSE vulnerability allows a local, unprivileged user to overwrite arbitrary files on the system.

There is no known work around at this time.

All FUSE users should upgrade to the latest version:


      # emerge --sync
      # emerge --ask --oneshot --verbose ">=sys-fs/fuse-2.9.4"

CVE-2015-3202 BlueKnight b-man