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Ubuntu Security Notice USN-4951-1
May 12, 2021

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

- Ubuntu 20.10
- Ubuntu 20.04 LTS
- Ubuntu 18.04 LTS

Summary:

A Flatpak application could access files that it would not normally
be permitted to access.

Software Description:
- flatpak: Application deployment framework for desktop apps

Details:

Anton Lydike discovered that Flatpak did not properly handle special tokens
in desktop files. An attacker could use this to specially craft a Flatpak
application that could escape sandbox confinement.

Update instructions:

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

Ubuntu 20.10:
  flatpak                         1.8.2-1ubuntu0.2
  libflatpak0                     1.8.2-1ubuntu0.2

Ubuntu 20.04 LTS:
  flatpak                         1.6.5-0ubuntu0.3
  libflatpak0                     1.6.5-0ubuntu0.3

Ubuntu 18.04 LTS:
  flatpak                         1.0.9-0ubuntu0.3
  libflatpak0                     1.0.9-0ubuntu0.3

In general, a standard system update will make all the necessary changes.

References:
  https://ubuntu.com/security/notices/USN-4951-1
  CVE-2021-21381

Package Information:
  https://launchpad.net/ubuntu/+source/flatpak/1.8.2-1ubuntu0.2
  https://launchpad.net/ubuntu/+source/flatpak/1.6.5-0ubuntu0.3
  https://launchpad.net/ubuntu/+source/flatpak/1.0.9-0ubuntu0.3