Arch Linux Security Advisory ASA-202101-40 ========================================== Severity: High Date : 2021-01-20 CVE-ID : CVE-2021-21261 Package : flatpak Type : sandbox escape Remote : No Link : https://security.archlinux.org/AVG-1454 Summary ======= The package flatpak before version 1.10.0-1 is vulnerable to sandbox escape. Resolution ========== Upgrade to 1.10.0-1. # pacman -Syu "flatpak>=1.10.0-1" The problem has been fixed upstream in version 1.10.0. Workaround ========== None. Description =========== 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 the 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. Impact ====== A malicious application could execute arbitrary code on the host. References ========== https://github.com/flatpak/flatpak/security/advisories/GHSA-4ppf-fxf6-vxg2 https://github.com/flatpak/flatpak/commit/6d1773d2a54dde9b099043f07a2094a4f1... https://github.com/flatpak/flatpak/commit/821249844bbb7e52cbf4508b4de18c05e8... https://github.com/flatpak/flatpak/commit/6e5ae7a109cdfa9735ea7ccbd8cb79f9e8... https://github.com/flatpak/flatpak/commit/aeb6a7ab0abaac4a8f4ad98b3df476d9de... https://github.com/flatpak/flatpak/commit/39a5621e6941b9d27bf89b63e8fb6cad6e... https://github.com/flatpak/flatpak/commit/cc1401043c075268ecc652eac557ef8076... https://github.com/flatpak/flatpak/commit/d19f6c330aa42e17df6dc36d12b6f4dfa5... https://security.archlinux.org/CVE-2021-21261