The fusermount utility from FUSE can be abused to corrupt the /etc/mtab file contents, potentially allowing a local attacker to set unauthorized mount options.
|Package||sys-fs/fuse on all architectures|
|Affected versions||< 2.4.1-r1|
|Unaffected versions||>= 2.4.1-r1|
FUSE (Filesystem in Userspace) allows implementation of a fully functional filesystem in a userspace program. The fusermount utility is used to mount/unmount FUSE file systems.
Thomas Biege discovered that fusermount fails to securely handle special characters specified in mount points.
A local attacker could corrupt the contents of the /etc/mtab file by mounting over a maliciously-named directory using fusermount, potentially allowing the attacker to set unauthorized mount options. This is possible only if fusermount is installed setuid root, which is the default in Gentoo.
There is no known workaround at this time.
All FUSE users should upgrade to the latest version:
# emerge --sync # emerge --ask --oneshot --verbose ">=sys-fs/fuse-2.4.1-r1"
November 22, 2005
November 22, 2005: 01