xfree86 - several vulnerabilities

A number of vulnerabilities have been discovered in XFree86. The corrections
are listed below with the identification from the Common
Vulnerabilities and Exposures (CVE) project:

• CAN-2004-0083:

Buffer overflow in ReadFontAlias from dirfile.c of
XFree86 4.1.0 through 4.3.0 allows local users and remote attackers to
execute arbitrary code via a font alias file (font.alias) with a long
token, a different vulnerability than CAN-2004-0084.

• CAN-2004-0084:

Buffer overflow in the ReadFontAlias function in XFree86
4.1.0 to 4.3.0, when using the CopyISOLatin1Lowered function, allows
local or remote authenticated users to execute arbitrary code via a
malformed entry in the font alias (font.alias) file, a different
vulnerability than CAN-2004-0083.

• CAN-2004-0106:

Miscellaneous additional flaws in XFree86’s handling of
font files.

• CAN-2003-0690:

xdm does not verify whether the pam_setcred function call
succeeds, which may allow attackers to gain root privileges by
triggering error conditions within PAM modules, as demonstrated in
certain configurations of the MIT pam_krb5 module.

• CAN-2004-0093, CAN-2004-0094:

Denial-of-service attacks against the X
server by clients using the GLX extension and Direct Rendering
Infrastructure are possible due to unchecked client data (out-of-bounds
array indexes [CAN-2004-0093] and integer signedness errors
[CAN-2004-0094]).

Exploitation of CAN-2004-0083, CAN-2004-0084, CAN-2004-0106,
CAN-2004-0093 and CAN-2004-0094 would require a connection to the X
server. By default, display managers in Debian start the X server
with a configuration which only accepts local connections, but if the
configuration is changed to allow remote connections, or X servers are
started by other means, then these bugs could be exploited remotely.
Since the X server usually runs with root privileges, these bugs could
potentially be exploited to gain root privileges.

No attack vector for CAN-2003-0690 is known at this time.

For the stable distribution (woody) these problems have been fixed in
version 4.1.0-16woody3.

For the unstable distribution (sid) these problems have been fixed in
version 4.3.0-2.

We recommend that you update your xfree86 package.