CVE-2022-21682: Debian Linux

Medium severity, CVSS 6.5. EPSS: 1.7% chance of exploitation in the next 30 days.

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`.

Affected products

• Debian Debian Linux: version 9.0 only; version 10.0 only; version 11.0 only
• Fedoraproject Fedora: version 35 only
• Flatpak Flatpak: before 1.10.7 (fixed in 1.10.7); from 1.11.1, before 1.12.4 (fixed in 1.12.4)
• Flatpak Flatpak-Builder: before 1.2.2 (fixed in 1.2.2)
• Red Hat Enterprise Linux: version 8.0 only

Published 2022-01-13. Last modified 2026-06-17.