8.8
HIGH
CVE-2021-21261
"Flatpak Flatpak-Portal Sandbox Escape"
Description

Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. A bug was discovered in the `flatpak-portal` service that can allow sandboxed applications to execute arbitrary code on the host system (a sandbox escape). This sandbox-escape bug is present in versions from 0.11.4 and before fixed versions 1.8.5 and 1.10.0. The Flatpak portal D-Bus service (`flatpak-portal`, also known by its D-Bus service name `org.freedesktop.portal.Flatpak`) allows apps in a Flatpak sandbox to launch their own subprocesses in a new sandbox instance, either with the same security settings as the caller or with more restrictive security settings. For example, this is used in Flatpak-packaged web browsers such as Chromium to launch subprocesses that will process untrusted web content, and give those subprocesses a more restrictive sandbox than the browser itself. In vulnerable versions, the Flatpak portal service passes caller-specified environment variables to non-sandboxed processes on the host system, and in particular to the `flatpak run` command that is used to launch the new sandbox instance. A malicious or compromised Flatpak app could set environment variables that are trusted by the `flatpak run` command, and use them to execute arbitrary code that is not in a sandbox. As a workaround, this vulnerability can be mitigated by preventing the `flatpak-portal` service from starting, but that mitigation will prevent many Flatpak apps from working correctly. This is fixed in versions 1.8.5 and 1.10.0.

INFO

Published Date :

Jan. 14, 2021, 8:15 p.m.

Last Modified :

Jan. 27, 2021, 7:34 p.m.

Source :

[email protected]

Remotely Exploitable :

No

Impact Score :

6.0

Exploitability Score :

2.0
Affected Products

The following products are affected by CVE-2021-21261 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 Debian debian_linux
1 Flatpak flatpak
: Total Affected Vendor : 2 | Products : 2
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-2021-21261.

URL Resource
https://github.com/flatpak/flatpak/commit/6d1773d2a54dde9b099043f07a2094a4f1c2f486 Patch Third Party Advisory
https://github.com/flatpak/flatpak/commit/6e5ae7a109cdfa9735ea7ccbd8cb79f9e8d3ae8b Patch Third Party Advisory
https://github.com/flatpak/flatpak/commit/aeb6a7ab0abaac4a8f4ad98b3df476d9de6b8bd4 Patch Third Party Advisory
https://github.com/flatpak/flatpak/commit/cc1401043c075268ecc652eac557ef8076b5eaba Third Party Advisory
https://github.com/flatpak/flatpak/releases/tag/1.8.5 Third Party Advisory
https://github.com/flatpak/flatpak/security/advisories/GHSA-4ppf-fxf6-vxg2 Third Party Advisory
https://security.gentoo.org/glsa/202101-21 Third Party Advisory
https://www.debian.org/security/2021/dsa-4830 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-2021-21261 vulnerability anywhere in the article.

The following table lists the changes that have been made to the CVE-2021-21261 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
  • Modified Analysis by [email protected]

    Jan. 27, 2021

    Action Type Old Value New Value
    Removed CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
    Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H
    Changed Reference Type https://github.com/flatpak/flatpak/commit/6d1773d2a54dde9b099043f07a2094a4f1c2f486 No Types Assigned https://github.com/flatpak/flatpak/commit/6d1773d2a54dde9b099043f07a2094a4f1c2f486 Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/6e5ae7a109cdfa9735ea7ccbd8cb79f9e8d3ae8b No Types Assigned https://github.com/flatpak/flatpak/commit/6e5ae7a109cdfa9735ea7ccbd8cb79f9e8d3ae8b Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/aeb6a7ab0abaac4a8f4ad98b3df476d9de6b8bd4 No Types Assigned https://github.com/flatpak/flatpak/commit/aeb6a7ab0abaac4a8f4ad98b3df476d9de6b8bd4 Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/cc1401043c075268ecc652eac557ef8076b5eaba No Types Assigned https://github.com/flatpak/flatpak/commit/cc1401043c075268ecc652eac557ef8076b5eaba Third Party Advisory
    Changed Reference Type https://security.gentoo.org/glsa/202101-21 No Types Assigned https://security.gentoo.org/glsa/202101-21 Third Party Advisory
  • CVE Modified by [email protected]

    Jan. 26, 2021

    Action Type Old Value New Value
    Added Reference https://security.gentoo.org/glsa/202101-21 [No Types Assigned]
  • CVE Modified by [email protected]

    Jan. 22, 2021

    Action Type Old Value New Value
    Changed Description Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. A bug was discovered in the `flatpak-portal` service that can allow sandboxed applications to execute arbitrary code on the host system (a sandbox escape). This sandbox-escape bug is present in versions from 0.11.4 and before fixed versions 1.8.5 and 1.9.4. The Flatpak portal D-Bus service (`flatpak-portal`, also known by its D-Bus service name `org.freedesktop.portal.Flatpak`) allows apps in a Flatpak sandbox to launch their own subprocesses in a new sandbox instance, either with the same security settings as the caller or with more restrictive security settings. For example, this is used in Flatpak-packaged web browsers such as Chromium to launch subprocesses that will process untrusted web content, and give those subprocesses a more restrictive sandbox than the browser itself. In vulnerable versions, the Flatpak portal service passes caller-specified environment variables to non-sandboxed processes on the host system, and in particular to the `flatpak run` command that is used to launch the new sandbox instance. A malicious or compromised Flatpak app could set environment variables that are trusted by the `flatpak run` command, and use them to execute arbitrary code that is not in a sandbox. As a workaround, this vulnerability can be mitigated by preventing the `flatpak-portal` service from starting, but that mitigation will prevent many Flatpak apps from working correctly. This is fixed in versions 1.8.5 and 1.9.4. Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. A bug was discovered in the `flatpak-portal` service that can allow sandboxed applications to execute arbitrary code on the host system (a sandbox escape). This sandbox-escape bug is present in versions from 0.11.4 and before fixed versions 1.8.5 and 1.10.0. The Flatpak portal D-Bus service (`flatpak-portal`, also known by its D-Bus service name `org.freedesktop.portal.Flatpak`) allows apps in a Flatpak sandbox to launch their own subprocesses in a new sandbox instance, either with the same security settings as the caller or with more restrictive security settings. For example, this is used in Flatpak-packaged web browsers such as Chromium to launch subprocesses that will process untrusted web content, and give those subprocesses a more restrictive sandbox than the browser itself. In vulnerable versions, the Flatpak portal service passes caller-specified environment variables to non-sandboxed processes on the host system, and in particular to the `flatpak run` command that is used to launch the new sandbox instance. A malicious or compromised Flatpak app could set environment variables that are trusted by the `flatpak run` command, and use them to execute arbitrary code that is not in a sandbox. As a workaround, this vulnerability can be mitigated by preventing the `flatpak-portal` service from starting, but that mitigation will prevent many Flatpak apps from working correctly. This is fixed in versions 1.8.5 and 1.10.0.
    Removed Reference https://github.com/flatpak/flatpak/commit/57416f380600d9754df12baf5b227144ff1bb54d [Patch, Third Party Advisory]
    Removed Reference https://github.com/flatpak/flatpak/commit/6a11007021658518c088ba0cc5e4da27962a940a [Patch, Third Party Advisory]
    Removed Reference https://github.com/flatpak/flatpak/commit/dcd24941c7087c5f7e8033abe50b178ac02a34af [Patch, Third Party Advisory]
    Removed Reference https://github.com/flatpak/flatpak/commit/fb1eaefbceeb73f02eb1bc85865d74a414faf8b8 [Patch, Third Party Advisory]
    Added Reference https://github.com/flatpak/flatpak/commit/cc1401043c075268ecc652eac557ef8076b5eaba [No Types Assigned]
    Added Reference https://github.com/flatpak/flatpak/commit/6d1773d2a54dde9b099043f07a2094a4f1c2f486 [No Types Assigned]
    Added Reference https://github.com/flatpak/flatpak/commit/aeb6a7ab0abaac4a8f4ad98b3df476d9de6b8bd4 [No Types Assigned]
    Added Reference https://github.com/flatpak/flatpak/commit/6e5ae7a109cdfa9735ea7ccbd8cb79f9e8d3ae8b [No Types Assigned]
  • Initial Analysis by [email protected]

    Jan. 22, 2021

    Action Type Old Value New Value
    Added CVSS V2 NIST (AV:L/AC:L/Au:N/C:C/I:C/A:C)
    Added CVSS V3.1 NIST AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:L/A:N
    Changed Reference Type https://github.com/flatpak/flatpak/commit/57416f380600d9754df12baf5b227144ff1bb54d No Types Assigned https://github.com/flatpak/flatpak/commit/57416f380600d9754df12baf5b227144ff1bb54d Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/6a11007021658518c088ba0cc5e4da27962a940a No Types Assigned https://github.com/flatpak/flatpak/commit/6a11007021658518c088ba0cc5e4da27962a940a Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/dcd24941c7087c5f7e8033abe50b178ac02a34af No Types Assigned https://github.com/flatpak/flatpak/commit/dcd24941c7087c5f7e8033abe50b178ac02a34af Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/commit/fb1eaefbceeb73f02eb1bc85865d74a414faf8b8 No Types Assigned https://github.com/flatpak/flatpak/commit/fb1eaefbceeb73f02eb1bc85865d74a414faf8b8 Patch, Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/releases/tag/1.8.5 No Types Assigned https://github.com/flatpak/flatpak/releases/tag/1.8.5 Third Party Advisory
    Changed Reference Type https://github.com/flatpak/flatpak/security/advisories/GHSA-4ppf-fxf6-vxg2 No Types Assigned https://github.com/flatpak/flatpak/security/advisories/GHSA-4ppf-fxf6-vxg2 Third Party Advisory
    Changed Reference Type https://www.debian.org/security/2021/dsa-4830 No Types Assigned https://www.debian.org/security/2021/dsa-4830 Third Party Advisory
    Added CPE Configuration OR *cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:* versions from (including) 0.11.4 up to (excluding) 1.8.5 *cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:* versions from (including) 1.9.1 up to (excluding) 1.10.0
    Added CPE Configuration OR *cpe:2.3:o:debian:debian_linux:10.0:*:*:*:*:*:*:*
  • CVE Modified by [email protected]

    Jan. 17, 2021

    Action Type Old Value New Value
    Added Reference https://www.debian.org/security/2021/dsa-4830 [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-2021-21261 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-2021-21261 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.

0.05 }} 0.00%

score

0.19788

percentile

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