libXfont could be made to access arbitrary files, including special device files.
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.
29 November 2017
A security issue affects these releases of Ubuntu and its derivatives:
libXfont could be made to access arbitrary files, including special device files.
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.
The problem can be corrected by updating your system to the following package versions:
To update your system, please follow these instructions: https://wiki.ubuntu.com/Security/Upgrades.
After a standard system update you need to reboot your computer to make all the necessary changes.