Flatpak up to 1.10.5/1.12.2 Metadata File privileges management

CVSS Meta Temp Score
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8.3$0-$5k0.00

A vulnerability classified as critical was found in Flatpak up to 1.10.5/1.12.2. This vulnerability affects an unknown code block of the component Metadata File Handler. The manipulation with an unknown input leads to a privilege escalation vulnerability. The CWE definition for the vulnerability is CWE-269. As an impact it is known to affect confidentiality, integrity, and availability. CVE summarizes:

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.

The weakness was released 01/13/2022 as GHSA-qpjc-vq3c-572j. The advisory is shared for download at github.com. This vulnerability was named CVE-2021-43860 since 11/16/2021. The exploitation appears to be easy. The attack can be initiated remotely. The requirement for exploitation is a single authentication. There are neither technical details nor an exploit publicly available.

Upgrading to version 1.10.6 or 1.12.3 eliminates this vulnerability. The upgrade is hosted for download at github.com. Applying the patch 54ec1a482dfc668127eaae57f135e6a8e0bc52da is able to eliminate this problem. The bugfix is ready for download at github.com. The best possible mitigation is suggested to be upgrading to the latest version.

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CPE 2.3infoedit

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CVSSv3infoedit

VulDB Meta Base Score: 8.5
VulDB Meta Temp Score: 8.3

VulDB Base Score: 8.8
VulDB Temp Score: 8.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 8.2
CNA Vector (GitHub, Inc.): 🔒

CVSSv2infoedit

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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfoedit

Class: Privilege escalation
CWE: CWE-269
ATT&CK: Unknown

Local: No
Remote: Yes

Availability: 🔒
Status: Not defined
Price Prediction: 🔍
Current Price Estimation: 🔒

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Threat Intelligenceinfoedit

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfoedit

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Upgrade: Flatpak 1.10.6/1.12.3
Patch: 54ec1a482dfc668127eaae57f135e6a8e0bc52da

Timelineinfoedit

11/16/2021 CVE assigned
01/13/2022 +58 days Advisory disclosed
01/13/2022 +0 days VulDB entry created
01/15/2022 +2 days VulDB last update

Sourcesinfoedit

Advisory: GHSA-qpjc-vq3c-572j
Status: Confirmed
Confirmation: 🔒

CVE: CVE-2021-43860 (🔒)

Entryinfoedit

Created: 01/13/2022 06:29 AM
Updated: 01/15/2022 11:53 AM
Changes: (1) source_cve_nvd_summary
Complete: 🔍

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