Path Traversal in Flatpak
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`.
Vulnerability class: Path Traversal (Directory Traversal)
Published · last modified .
CVSS v3 metric
CVSS v3 base score 7.7 (High). Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:N/I:H/A:N.
EPSS exploit prediction
EPSS: 0.017 (76.0th percentile), scored .
Low probability of exploitation in the next 30 days, but still tracked. 76th percentile — 76.0% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.017 · newest: 0.017 · change: 0.000
Affected products
- Flatpak — versions >= 1.11.0, < 1.12.3, < 1.10.6
- Flatpak Flatpak-Builder
- Debian Linux — versions 9.0, 10.0, 11.0
- Fedoraproject Fedora — versions 35
- Red Hat Enterprise Linux — versions 8.0
Weakness classification (CWE)
Public proof-of-concept exploits
References
- github.com/flatpak/flatpak/security/advisories/GHSA-8ch7-5j3h-g4fx (Patch, Third Party Advisory)
- github.com/flatpak/flatpak/commit/445bddeee657fdc8d2a0a1f0de12975400d4fc1a (Patch, Third Party Advisory)
- github.com/flatpak/flatpak/commit/4d11f77aa7fd3e64cfa80af89d92567ab9e8e6fa (Patch, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- www.debian.org/security/2022/dsa-5049 (vendor-advisory, Third Party Advisory)
- lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/… (vendor-advisory)
- security.gentoo.org/glsa/202312-12 (vendor-advisory)
Frequently asked questions
- What is CVE-2022-21682?
- CVE-2022-21682 is a high-severity vulnerability in Flatpak, classified under Path Traversal. CVSS score: 7.7/10. Published 2022-01-13.
- How severe is CVE-2022-21682?
- High severity. CVSS v3 base score is 7.7 out of 10.
- Is CVE-2022-21682 known to be exploited?
- 3 public proof-of-concept repositories are indexed. Not currently listed in the CISA KEV catalog.