[gentoo-announce] [ GLSA 201603-04 ] FUSE: incorrect filtering of environment variables leading to privilege escalation

[news 28]

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

Gentoo Linux Security Advisory GLSA 201603-04

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

https://security.gentoo.org/

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 

Severity: Normal

Title: FUSE: incorrect filtering of environment variables leading to

privilege escalation

Date: March 09, 2016

Bugs: #550152

ID: 201603-04

 

- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -

 

Synopsis

========

 

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.

 

Background

==========

 

FUSE provides an interface for filesystems implemented in userspace.

 

Affected packages

=================

 

-------------------------------------------------------------------

Package / Vulnerable / Unaffected

-------------------------------------------------------------------

1 sys-fs/fuse < 2.9.4 >= 2.9.4

 

Description

===========

 

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.

 

Impact

======

 

The FUSE vulnerability allows a local, unprivileged user to overwrite

arbitrary files on the system.

 

Workaround

==========

 

There is no known work around at this time.

 

Resolution

==========

 

All FUSE users should upgrade to the latest version:

 

# emerge --sync

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

 

References

==========

 

[ 1 ] CVE-2015-3202

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2015-3202

 

Availability

============

 

This GLSA and any updates to it are available for viewing at

the Gentoo Security Website:

 

https://security.gentoo.org/glsa/201603-04

 

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 ( -at -) gentoo.org or alternatively, you may file a bug at

https://bugs.gentoo.org.

 

License

=======

 

Copyright 2016 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/2.5