[ GLSA 200511-17 ] FUSE: mtab corruption through fusermount

[Thierry Carrez]

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Gentoo Linux Security Advisory GLSA 200511-17
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http://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:

http://security.gentoo.org/glsa/glsa-200511-17.xml

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
http://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.

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


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