8.2
HIGH
CVE-2021-21381
Flatpak File Forwarding Token Injection Vulnerability
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`.

INFO

Published Date :

March 11, 2021, 5:15 p.m.

Last Modified :

Dec. 23, 2023, 10:15 a.m.

Source :

[email protected]

Remotely Exploitable :

No

Impact Score :

5.8

Exploitability Score :

1.8
Affected Products

The following products are affected by CVE-2021-21381 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

ID Vendor Product Action
1 Fedoraproject fedora
1 Debian debian_linux
1 Flatpak flatpak
: Total Affected Vendor : 3 | Products : 3
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2021-21381.

URL 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%40lists.fedoraproject.org/message/2MXXLXC2DPJ45HSMTI5MZYHMYEGQN6AA/
https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WXNVFOIB6ZP4DGOVKAM25T6OIEP3YLGV/
https://security.gentoo.org/glsa/202312-12
https://www.debian.org/security/2021/dsa-4868 Third Party Advisory

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2021-21381 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-21381 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • CVE Modified by [email protected]

    May. 14, 2024

    Action Type Old Value New Value
  • CVE Modified by [email protected]

    Dec. 23, 2023

    Action Type Old Value New Value
    Added Reference GitHub, Inc. https://security.gentoo.org/glsa/202312-12 [No types assigned]
  • CVE Modified by [email protected]

    Nov. 07, 2023

    Action Type Old Value New Value
    Added Reference GitHub, Inc. https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/WXNVFOIB6ZP4DGOVKAM25T6OIEP3YLGV/ [No types assigned]
    Added Reference GitHub, Inc. https://lists.fedoraproject.org/archives/list/package-announce%40lists.fedoraproject.org/message/2MXXLXC2DPJ45HSMTI5MZYHMYEGQN6AA/ [No types assigned]
    Removed Reference GitHub, Inc. https://lists.fedoraproject.org/archives/list/[email protected]/message/WXNVFOIB6ZP4DGOVKAM25T6OIEP3YLGV/
    Removed Reference GitHub, Inc. https://lists.fedoraproject.org/archives/list/[email protected]/message/2MXXLXC2DPJ45HSMTI5MZYHMYEGQN6AA/
  • Modified Analysis by [email protected]

    Mar. 25, 2021

    Action Type Old Value New Value
    Changed Reference Type https://lists.fedoraproject.org/archives/list/[email protected]/message/2MXXLXC2DPJ45HSMTI5MZYHMYEGQN6AA/ No Types Assigned https://lists.fedoraproject.org/archives/list/[email protected]/message/2MXXLXC2DPJ45HSMTI5MZYHMYEGQN6AA/ Mailing List, Third Party Advisory
    Changed Reference Type https://lists.fedoraproject.org/archives/list/[email protected]/message/WXNVFOIB6ZP4DGOVKAM25T6OIEP3YLGV/ No Types Assigned https://lists.fedoraproject.org/archives/list/[email protected]/message/WXNVFOIB6ZP4DGOVKAM25T6OIEP3YLGV/ Mailing List, Third Party Advisory
    Added CPE Configuration OR *cpe:2.3:o:fedoraproject:fedora:33:*:*:*:*:*:*:* *cpe:2.3:o:fedoraproject:fedora:34:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Mar. 19, 2021

    Action Type Old Value New Value
    Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/2MXXLXC2DPJ45HSMTI5MZYHMYEGQN6AA/ [No Types Assigned]
  • CVE Modified by [email protected]

    Mar. 19, 2021

    Action Type Old Value New Value
    Added Reference https://lists.fedoraproject.org/archives/list/[email protected]/message/WXNVFOIB6ZP4DGOVKAM25T6OIEP3YLGV/ [No Types Assigned]
  • Initial Analysis by [email protected]

    Mar. 19, 2021

    Action Type Old Value New Value
    Added CVSS V2 Metadata Victim must voluntarily interact with attack mechanism
    Added CVSS V2 NIST (AV:N/AC:M/Au:N/C:P/I:P/A:N)
    Added CVSS V3.1 NIST AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:N
    Changed Reference Type https://github.com/flatpak/flatpak/commit/8279c5818425b6812523e3805bbe242fb6a5d961 No Types Assigned https://github.com/flatpak/flatpak/commit/8279c5818425b6812523e3805bbe242fb6a5d961 Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/a7401e638bf0c03102039e216ab1081922f140ae No Types Assigned https://github.com/flatpak/flatpak/commit/a7401e638bf0c03102039e216ab1081922f140ae Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/eb7946bb6248923d8c90fe9b84425fef97ae580d No Types Assigned https://github.com/flatpak/flatpak/commit/eb7946bb6248923d8c90fe9b84425fef97ae580d Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/pull/4156 No Types Assigned https://github.com/flatpak/flatpak/pull/4156 Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/releases/tag/1.10.2 No Types Assigned https://github.com/flatpak/flatpak/releases/tag/1.10.2 Release Notes, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/security/advisories/GHSA-xgh4-387p-hqpp No Types Assigned https://github.com/flatpak/flatpak/security/advisories/GHSA-xgh4-387p-hqpp Third Party Advisory
    Changed Reference Type https://www.debian.org/security/2021/dsa-4868 No Types Assigned https://www.debian.org/security/2021/dsa-4868 Third Party Advisory
    Added CPE Configuration OR *cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:* versions from (including) 0.9.4 up to (excluding) 1.10.2
    Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Mar. 13, 2021

    Action Type Old Value New Value
    Added Reference https://www.debian.org/security/2021/dsa-4868 [No Types Assigned]
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2021-21381 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2021-21381 weaknesses.

CAPEC-3: Using Leading 'Ghost' Character Sequences to Bypass Input Filters Using Leading 'Ghost' Character Sequences to Bypass Input Filters CAPEC-6: Argument Injection Argument Injection CAPEC-7: Blind SQL Injection Blind SQL Injection CAPEC-8: Buffer Overflow in an API Call Buffer Overflow in an API Call CAPEC-9: Buffer Overflow in Local Command-Line Utilities Buffer Overflow in Local Command-Line Utilities CAPEC-10: Buffer Overflow via Environment Variables Buffer Overflow via Environment Variables CAPEC-13: Subverting Environment Variable Values Subverting Environment Variable Values CAPEC-14: Client-side Injection-induced Buffer Overflow Client-side Injection-induced Buffer Overflow CAPEC-24: Filter Failure through Buffer Overflow Filter Failure through Buffer Overflow CAPEC-28: Fuzzing Fuzzing CAPEC-34: HTTP Response Splitting HTTP Response Splitting CAPEC-42: MIME Conversion MIME Conversion CAPEC-43: Exploiting Multiple Input Interpretation Layers Exploiting Multiple Input Interpretation Layers CAPEC-45: Buffer Overflow via Symbolic Links Buffer Overflow via Symbolic Links CAPEC-46: Overflow Variables and Tags Overflow Variables and Tags CAPEC-47: Buffer Overflow via Parameter Expansion Buffer Overflow via Parameter Expansion CAPEC-51: Poison Web Service Registry Poison Web Service Registry CAPEC-52: Embedding NULL Bytes Embedding NULL Bytes CAPEC-53: Postfix, Null Terminate, and Backslash Postfix, Null Terminate, and Backslash CAPEC-64: Using Slashes and URL Encoding Combined to Bypass Validation Logic Using Slashes and URL Encoding Combined to Bypass Validation Logic CAPEC-67: String Format Overflow in syslog() String Format Overflow in syslog() CAPEC-71: Using Unicode Encoding to Bypass Validation Logic Using Unicode Encoding to Bypass Validation Logic CAPEC-72: URL Encoding URL Encoding CAPEC-76: Manipulating Web Input to File System Calls Manipulating Web Input to File System Calls CAPEC-78: Using Escaped Slashes in Alternate Encoding Using Escaped Slashes in Alternate Encoding CAPEC-79: Using Slashes in Alternate Encoding Using Slashes in Alternate Encoding CAPEC-80: Using UTF-8 Encoding to Bypass Validation Logic Using UTF-8 Encoding to Bypass Validation Logic CAPEC-83: XPath Injection XPath Injection CAPEC-84: XQuery Injection XQuery Injection CAPEC-101: Server Side Include (SSI) Injection Server Side Include (SSI) Injection CAPEC-105: HTTP Request Splitting HTTP Request Splitting CAPEC-108: Command Line Execution through SQL Injection Command Line Execution through SQL Injection CAPEC-120: Double Encoding Double Encoding CAPEC-135: Format String Injection Format String Injection CAPEC-250: XML Injection XML Injection CAPEC-267: Leverage Alternate Encoding Leverage Alternate Encoding CAPEC-273: HTTP Response Smuggling HTTP Response Smuggling
Exploit Prediction

EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days.

0.14 }} 0.02%

score

0.49856

percentile

CVSS31 - Vulnerability Scoring System
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality
Integrity
Availability
: