LibXfont, monolithic X.org: Multiple integer overflows

1. Gentoo Linux Security Advisory

Advisory Reference	GLSA 200609-07 / libxfont
Release Date	September 13, 2006
Latest Revision	September 13, 2006: 01
Impact	high
Exploitable	local and remote

Package	Vulnerable versions	Unaffected versions	Architecture(s)
x11-libs/libXfont	< 1.2.1	>= 1.2.1	All supported architectures
x11-base/xorg-x11	< 7.0	>= 7.0	All supported architectures

Related bugreports: #145513

Synopsis

Some buffer overflows were discovered in the CID font parser, potentially resulting in the execution of arbitrary code with elevated privileges.

2. Impact Information

Background

libXfont is the X.Org Xfont library, some parts are based on the FreeType code base.

Description

Several integer overflows have been found in the CID font parser.

Impact

A remote attacker could exploit this vulnerability by enticing a user to load a malicious font file resulting in the execution of arbitrary code with the permissions of the user running the X server which typically is the root user. A local user could exploit this vulnerability to gain elevated privileges.

3. Resolution Information

Workaround

Disable CID-encoded Type 1 fonts by removing the "type1" module and replacing it with the "freetype" module in xorg.conf.

Resolution

All libXfont users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=x11-libs/libXfont-1.2.1"

All monolithic X.org users are advised to migrate to modular X.org.

4. References

Updated September 13, 2006

Summary: This is a Gentoo Linux Security Advisory

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