gnome-desktop could be made to escape the thumbnailer sandbox.
It was discovered that gnome-desktop incorrectly confined thumbnailers. If a user were tricked into downloading a malicious image file, a remote attacker could possibly combine this issue with another vulnerability to escape the sandbox and execute arbitrary code.
27 May 2019
A security issue affects these releases of Ubuntu and its derivatives:
gnome-desktop could be made to escape the thumbnailer sandbox.
It was discovered that gnome-desktop incorrectly confined thumbnailers. If a user were tricked into downloading a malicious image file, a remote attacker could possibly combine this issue with another vulnerability to escape the sandbox and execute arbitrary code.
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 restart your session to make all the necessary changes.