libXfont -- X Font Service Protocol and Font metadata file handling issues

ID B060EE50-DABA-11E3-99F2-BCAEC565249C
Type freebsd
Reporter FreeBSD
Modified 2015-07-15T00:00:00


Alan Coopersmith reports:

Ilja van Sprundel, a security researcher with IOActive, has discovered several issues in the way the libXfont library handles the responses it receives from xfs servers, and has worked with X.Org's security team to analyze, confirm, and fix these issues. Most of these issues stem from libXfont trusting the font server to send valid protocol data, and not verifying that the values will not overflow or cause other damage. This code is commonly called from the X server when an X Font Server is active in the font path, so may be running in a setuid-root process depending on the X server in use. Exploits of this path could be used by a local, authenticated user to attempt to raise privileges; or by a remote attacker who can control the font server to attempt to execute code with the privileges of the X server.