USN-3500-1: libXfont vulnerability

29 November 2017

libxfont, libxfont1, libxfont2 vulnerability

A security issue affects these releases of Ubuntu and its derivatives:

  • Ubuntu 17.10
  • Ubuntu 17.04
  • Ubuntu 16.04 LTS
  • Ubuntu 14.04 LTS


libXfont could be made to access arbitrary files, including special device files.

Software Description

  • libxfont - X11 font rasterisation library
  • libxfont1 - X11 font rasterisation library
  • libxfont2 - X11 font rasterisation library


It was discovered that libXfont incorrectly followed symlinks when opening font files. A local unprivileged user could use this issue to cause the X server to access arbitrary files, including special device files.

Update instructions

The problem can be corrected by updating your system to the following package versions:

Ubuntu 17.10
libxfont1 - 1:1.5.2-4ubuntu1.1
libxfont2 - 1:2.0.1-3ubuntu1.1
Ubuntu 17.04
libxfont1 - 1:1.5.2-4ubuntu0.2
libxfont2 - 1:2.0.1-3ubuntu0.2
Ubuntu 16.04 LTS
libxfont1 - 1:1.5.1-1ubuntu0.16.04.4
libxfont2 - 1:2.0.1-3~ubuntu16.04.3
Ubuntu 14.04 LTS
libxfont1 - 1:1.4.7-1ubuntu0.4

To update your system, please follow these instructions:

After a standard system update you need to reboot your computer to make all the necessary changes.