A flatpak security update has been released for Debian GNU/Linux 10 to address a bug in the flatpak-portal service that can allow sandboxed applications to execute arbitrary code on the host system (a sandbox escape).

DSA 4830-1: flatpak security update

- -------------------------------------------------------------------------
Debian Security Advisory DSA-4830-1 security@debian.org
  https://www.debian.org/security/ Moritz Muehlenhoff
January 14, 2021   https://www.debian.org/security/faq
- -------------------------------------------------------------------------

Package : flatpak
CVE ID : not yet available

Simon McVittie discovered a bug in the flatpak-portal service that can
allow sandboxed applications to execute arbitrary code on the host system
(a sandbox escape).

The Flatpak portal D-Bus service (flatpak-portal, also known by its
D-Bus service name org.freedesktop.portal.Flatpak) allows apps in a
Flatpak sandbox to launch their own subprocesses in a new sandbox
instance, either with the same security settings as the caller or
with more restrictive security settings. For example, this is used in
Flatpak-packaged web browsers such as Chromium to launch subprocesses
that will process untrusted web content, and give those subprocesses a
more restrictive sandbox than the browser itself.

In vulnerable versions, the Flatpak portal service passes caller-specified
environment variables to non-sandboxed processes on the host system,
and in particular to the flatpak run command that is used to launch the
new sandbox instance. A malicious or compromised Flatpak app could set
environment variables that are trusted by the flatpak run command, and
use them to execute arbitrary code that is not in a sandbox.

For the stable distribution (buster), this problem has been fixed in
version 1.2.5-0+deb10u2.

We recommend that you upgrade your flatpak packages.

For the detailed security status of flatpak please refer to
its security tracker page at:
  https://security-tracker.debian.org/tracker/flatpak

Further information about Debian Security Advisories, how to apply
these updates to your system and frequently asked questions can be
found at:   https://www.debian.org/security/