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CVE-2021-43860 Detail

Current Description

Flatpak is a Linux application sandboxing and distribution framework. Prior to versions 1.12.3 and 1.10.6, Flatpak doesn't properly validate that the permissions displayed to the user for an app at install time match the actual permissions granted to the app at runtime, in the case that there's a null byte in the metadata file of an app. Therefore apps can grant themselves permissions without the consent of the user. Flatpak shows permissions to the user during install by reading them from the "xa.metadata" key in the commit metadata. This cannot contain a null terminator, because it is an untrusted GVariant. Flatpak compares these permissions to the *actual* metadata, from the "metadata" file to ensure it wasn't lied to. However, the actual metadata contents are loaded in several places where they are read as simple C-style strings. That means that, if the metadata file includes a null terminator, only the content of the file from *before* the terminator gets compared to xa.metadata. Thus, any permissions that appear in the metadata file after a null terminator are applied at runtime but not shown to the user. So maliciously crafted apps can give themselves hidden permissions. Users who have Flatpaks installed from untrusted sources are at risk in case the Flatpak has a maliciously crafted metadata file, either initially or in an update. This issue is patched in versions 1.12.3 and 1.10.6. As a workaround, users can manually check the permissions of installed apps by checking the metadata file or the xa.metadata key on the commit metadata.


View Analysis Description

Severity



CVSS 3.x Severity and Metrics:

NIST CVSS score
NIST: NVD
Base Score:  8.6 HIGH
Vector:  CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Nist CVSS score does not match with CNA score
CNA:  GitHub, Inc.
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


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/54ec1a482dfc668127eaae57f135e6a8e0bc52da Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/commit/65cbfac982cb1c83993a9e19aa424daee8e9f042 Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/commit/93357d357119093804df05acc32ff335839c6451 Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/commit/ba818f504c926baaf6e362be8159cfacf994310e Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/commit/d9a8f9d8ccc0b7c1135d0ecde006a75d25f66aee Patch  Third Party Advisory 
https://github.com/flatpak/flatpak/releases/tag/1.10.6 Release Notes  Third Party Advisory 
https://github.com/flatpak/flatpak/releases/tag/1.12.3 Release Notes  Third Party Advisory 
https://github.com/flatpak/flatpak/security/advisories/GHSA-qpjc-vq3c-572j Patch  Third Party Advisory 
https://lists.fedoraproject.org/archives/list/package-announce@lists.fedoraproject.org/message/APFTBYGJJVJPFVHRXUW5PII5XOAFI4KH/ Third Party Advisory 
https://www.debian.org/security/2022/dsa-5049 Third Party Advisory 

Weakness Enumeration

CWE-ID CWE Name Source
CWE-276 Incorrect Default Permissions cwe source acceptance level NIST  
CWE-269 Improper Privilege Management Contributor acceptance level GitHub, Inc.  

Known Affected Software Configurations Switch to CPE 2.2

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Change History

4 change records found show changes

Quick Info

CVE Dictionary Entry:
CVE-2021-43860
NVD Published Date:
01/12/2022
NVD Last Modified:
02/10/2022
Source:
GitHub, Inc.