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CVE-2021-21261

CVE information

Published

3 years ago

Last Modified

3 years ago

CVSSv2.0 Severity

High

CVSSv3.1 Severity

High

Impact Analysis

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Description

Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. A bug was discovered in the `flatpak-portal` service that can allow sandboxed applications to execute arbitrary code on the host system (a sandbox escape). This sandbox-escape bug is present in versions from 0.11.4 and before fixed versions 1.8.5 and 1.10.0. 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. As a workaround, this vulnerability can be mitigated by preventing the `flatpak-portal` service from starting, but that mitigation will prevent many Flatpak apps from working correctly. This is fixed in versions 1.8.5 and 1.10.0..

CVSSv2.0 Score

Severity
High
Base Score
7.2/10
Exploit Score
3.9/10
Access Vector
Local
Access Complexity
Low
Authentication Required
None
Impact Score
10/10
Confidentiality Impact
Complete
Availability Impact
Complete
Integrity Impact
Complete

CVSSv3.1 Score

Severity
High
Base Score
8.8/10
Exploit Score
2/10
Access Vector
Local
Access Complexity
Low
Privileges Required
Low
Impact Score
6/10
Confidentiality Impact
High
Availability Impact
High
Integrity Impact
High
Scope
Changed
User Interaction
None

Products Affected

CPE Affected Vulnerable Excluding Edit
cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*
  Yes
1.9.1 1.10.0
cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*
  Yes
0.11.4 1.8.5
cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
  Yes
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References