LibXfont, monolithic X.org: Multiple integer overflows

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.

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:

 # 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.