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Gentoo Linux Security Advisory                           GLSA 200511-17
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                                            https://security.gentoo.org/
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  Severity: Normal
     Title: FUSE: mtab corruption through fusermount
      Date: November 22, 2005
      Bugs: #112902
        ID: 200511-17

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Synopsis
=======
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.

Background
=========
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.

Affected packages
================
    -------------------------------------------------------------------
     Package      /  Vulnerable  /                          Unaffected
    -------------------------------------------------------------------
  1  sys-fs/fuse     < 2.4.1-r1                            >= 2.4.1-r1

Description
==========
Thomas Biege discovered that fusermount fails to securely handle
special characters specified in mount points.

Impact
=====
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.

Workaround
=========
There is no known workaround at this time.

Resolution
=========
All FUSE users should upgrade to the latest version:

    # emerge --sync
    # emerge --ask --oneshot --verbose ">=sys-fs/fuse-2.4.1-r1"

References
=========
  [ 1 ] CVE-2005-3531
        http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2005-3531

Availability
===========
This GLSA and any updates to it are available for viewing at
the Gentoo Security Website:

  https://security.gentoo.org/glsa/200511-17

Concerns?
========
Security is a primary focus of Gentoo Linux and ensuring the
confidentiality and security of our users machines is of utmost
importance to us. Any security concerns should be addressed to
security@gentoo.org or alternatively, you may file a bug at
https://bugs.gentoo.org/.

License
======
Copyright 2005 Gentoo Foundation, Inc; referenced text
belongs to its owner(s).

The contents of this document are licensed under the
Creative Commons - Attribution / Share Alike license.

https://creativecommons.org/licenses/by-sa/2.0/