CVE-2021-21381 Detail

Current 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`.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  8.2 HIGH
Vector:  CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N

Nist CVSS score does not match with CNA score
CNA:  GitHub, Inc.
Base Score:  7.1 HIGH
Vector:  CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:L/I:H/A:N


NVD Analysts use publicly available information to associate vector strings and CVSS scores. We also display any CVSS information provided within the CVE List from the CNA.

Note: It is possible that the NVD CVSS may not match that of the CNA. The most common reason for this is that publicly available information does not provide sufficient detail or that information simply was not available at the time the CVSS vector string was assigned.

References to Advisories, Solutions, and Tools

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Hyperlink Resource
https://github.com/flatpak/flatpak/commit/8279c5818425b6812523e3805bbe242fb6a5d961 Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/commit/a7401e638bf0c03102039e216ab1081922f140ae Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/commit/eb7946bb6248923d8c90fe9b84425fef97ae580d Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/pull/4156 Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/releases/tag/1.10.2 Release Notes  Third Party Advisory 
https://github.com/flatpak/flatpak/security/advisories/GHSA-xgh4-387p-hqpp Third Party Advisory 
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/2MXXLXC2DPJ45HSMTI5MZYHMYEGQN6AA/ Mailing List  Third Party Advisory 
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/WXNVFOIB6ZP4DGOVKAM25T6OIEP3YLGV/ Mailing List  Third Party Advisory 
https://www.debian.org/security/2021/dsa-4868 Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') Provider acceptance level GitHub, Inc.  

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Change History

5 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2021-21381
NVD Published Date:
03/11/2021
NVD Last Modified:
03/24/2021
Source:
GitHub, Inc.