CVE-2021-21381

CVE Details

Release Date:	2021-03-11
Impact:	None	What is this?

Description

Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. In Flatpack since version 0.9.4 and before version 1.10.2 has a vulnerability in the "file forwarding" feature which can be used by an attacker to gain access to files that would not ordinarily be allowed by the app's permissions. By putting the special tokens @@ and/or @@u in the Exec field of a Flatpak app's .desktop file, a malicious app publisher can trick flatpak into behaving as though the user had chosen to open a target file with their Flatpak app, which automatically makes that file available to the Flatpak app. This is fixed in version 1.10.2. A minimal solution is the first commit "Disallow @@ and @@U usage in desktop files". The follow-up commits "dir: Reserve the whole @@ prefix" and "dir: Refuse to export .desktop files with suspicious uses of @@ tokens" are recommended, but not strictly required. As a workaround, avoid installing Flatpak apps from untrusted sources, or check the contents of the exported .desktop files in exports/share/applications/*.desktop (typically ~/.local/share/flatpak/exports/share/applications/*.desktop and /var/lib/flatpak/exports/share/applications/*.desktop) to make sure that literal filenames do not follow @@ or @@u.

See more information about CVE-2021-21381 from MITRE CVE dictionary and NIST NVD

NOTE: The following CVSS metrics and score provided are preliminary and subject to review.

CVSS v3 metrics

Base Score:	8.2
Vector String:	CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
Version:	3.0
Attack Vector:	Local
Attack Complexity:	Low
Privileges Required:	None
User Interaction:	Required
Scope:	Changed
Confidentiality Impact:	High
Integrity Impact:	High
Availability Impact:	None

Errata information

Platform	Errata	Release Date
Oracle Linux version 7 (flatpak)	ELSA-2021-1002	2021-03-29
Oracle Linux version 8 (flatpak)	ELSA-2021-1068	2021-04-07