Multiple vulnerabilities have been discovered in the X.Org X server and
Xfont library, allowing for a local privilege escalation and arbitrary code
execution.
Background
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).
Impact
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 X.org 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.
Workaround
Workarounds for some of the vulnerabilities can be found in the X.Org
security advisory as listed under References.
Resolution
All X.Org X server users should upgrade to the latest version:
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.