Debian DSA-4830-1 : flatpak - security update

high Nessus Plugin ID 145021

Synopsis

The remote Debian host is missing a security-related update.

Description

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.

Solution

Upgrade the flatpak packages.

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

See Also

https://security-tracker.debian.org/tracker/source-package/flatpak

https://packages.debian.org/source/buster/flatpak

https://www.debian.org/security/2021/dsa-4830

Plugin Details

Severity: High

ID: 145021

File Name: debian_DSA-4830.nasl

Version: 1.5

Type: local

Agent: unix

Published: 1/15/2021

Updated: 1/29/2021

Supported Sensors: Frictionless Assessment Agent, Nessus Agent

Risk Information

CVSS Score Source: CVE-2021-21261

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: High

Base Score: 7.2

Temporal Score: 5.3

Vector: AV:L/AC:L/Au:N/C:C/I:C/A:C

Temporal Vector: E:U/RL:OF/RC:C

CVSS v3

Risk Factor: High

Base Score: 8.8

Temporal Score: 7.7

Vector: CVSS:3.0/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H

Temporal Vector: E:U/RL:O/RC:C

Vulnerability Information

CPE: p-cpe:/a:debian:debian_linux:flatpak, cpe:/o:debian:debian_linux:10.0

Required KB Items: Host/local_checks_enabled, Host/Debian/release, Host/Debian/dpkg-l

Exploit Ease: No known exploits are available

Patch Publication Date: 1/14/2021

Vulnerability Publication Date: 1/14/2021

Reference Information

CVE: CVE-2021-21261

DSA: 4830