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CVE-2022-21682

flatpak-builder can access files outside the build directory.

Published
Last modified
published
Not listed in CISA KEV
Fix
Fixed in 1.12.3, 1.10.6
None on Exploit-DB, Metasploit or GitHub

Summary

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`.

Timeline

  1. CVE published
  2. Record last updated

Affected versions

  • flatpak flatpak

    From 1.11.0 · fixed in 1.12.3; fixed in 1.10.6

References 7

GitHub · flatpak/flatpak

lists.fedoraproject.org

debian.org

security.gentoo.org