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X.Org X server and Xfont library: Multiple vulnerabilities


1.  Gentoo Linux Security Advisory

Version Information

Advisory Reference GLSA 200801-09 / xorg-server libXfont
Release Date January 20, 2008
Latest Revision March 05, 2008: 03
Impact high
Exploitable remote, local
Package Vulnerable versions Unaffected versions Architecture(s)
x11-base/xorg-server < >= All supported architectures
x11-libs/libXfont < 1.3.1-r1 >= 1.3.1-r1 All supported architectures

Related bugreports: #204362, #208343


Multiple vulnerabilities have been discovered in the X.Org X server and Xfont library, allowing for a local privilege escalation and arbitrary code execution.

2.  Impact Information


The X Window System is a graphical windowing system based on a client/server model.


regenrecht reported multiple vulnerabilities in various X server extension via iDefense:

  • The XFree86-Misc extension does not properly sanitize a parameter within a PassMessage request, allowing the modification of a function pointer (CVE-2007-5760).
  • Multiple functions in the XInput extension do not properly sanitize client requests for swapping bytes, leading to corruption of heap memory (CVE-2007-6427).
  • Integer overflow vulnerabilities in the EVI extension and in the MIT-SHM extension can lead to buffer overflows (CVE-2007-6429).
  • The TOG-CUP extension does not sanitize an index value in the ProcGetReservedColormapEntries() function, leading to arbitrary memory access (CVE-2007-6428).
  • A buffer overflow was discovered in the Xfont library when processing PCF font files (CVE-2008-0006).
  • The X server does not enforce restrictions when a user specifies a security policy file and attempts to open it (CVE-2007-5958).


Remote attackers could exploit the vulnerability in the Xfont library by enticing a user to load a specially crafted PCF font file resulting in the execution of arbitrary code with the privileges of the user running the X server, typically root. Local attackers could exploit this and the vulnerabilities in the extensions to gain elevated privileges. If the X server allows connections from the network, these vulnerabilities could be exploited remotely. A local attacker could determine the existence of arbitrary files by exploiting the last vulnerability or possibly cause a Denial of Service.

3.  Resolution Information


Workarounds for some of the vulnerabilities can be found in the X.Org security advisory as listed under References.


All X.Org X server users should upgrade to the latest version:

Code Listing 3.1: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=x11-base/xorg-server-"

All X.Org Xfont library users should upgrade to the latest version:

Code Listing 3.2: Resolution

# emerge --sync
# emerge --ask --oneshot --verbose ">=x11-libs/libXfont-1.3.1-r1"

4.  References


Page updated January 20, 2008

Summary: This is a Gentoo Linux Security Advisory

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