CVE-2022-21682

Date: January 12, 2022

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".

Language: C