CVE-2022-21682

Flatpak is a Linux application sandboxing and distribution framework. A path traversal vulnerability affects versions of Flatpak prior to 1.12.3 and 1.10.6. flatpak-builder applies `finish-args` last in the build. At this point the build directory will have the full access that is specified in the manifest, so running `flatpak build` against it will gain those permissions. Normally this will not be done, so this is not problem. However, if `--mirror-screenshots-url` is specified, then flatpak-builder will launch `flatpak build --nofilesystem=host appstream-utils mirror-screenshots` after finalization, which can lead to issues even with the `--nofilesystem=host` protection. In normal use, the only issue is that these empty directories can be created wherever the user has write permissions. However, a malicious application could replace the `appstream-util` binary and potentially do something more hostile. This has been resolved in Flatpak 1.12.3 and 1.10.6 by changing the behaviour of `--nofilesystem=home` and `--nofilesystem=host`.

• Debian

  OS
  Debian
  10.011.09.0

• Fedora Project Fedora

  OS
  Fedoraproject
  35

• Flatpak

  APP
  Flatpak
  < 1.10.71.11.1 – 1.12.4 (bez)

• Flatpak Builder

  APP
  Flatpak
  < 1.2.2

• Red Hat Enterprise Linux

  OS
  Redhat
  8.0