Unity Linux 20.1070e Security Update: flatpak (UTSA-2025-680646)

high Nessus Plugin ID 267706

Synopsis

The Unity Linux host is missing one or more security updates.

Description

The Unity Linux 20 host has a package installed that is affected by a vulnerability as referenced in the UTSA-2025-680646 advisory.

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.

Tenable has extracted the preceding description block directly from the Unity Linux security advisory.

Note that Nessus has not tested for this issue but has instead relied only on the application's self-reported version number.

Solution

Update the affected flatpak package.

Plugin Details

Severity: High

ID: 267706

File Name: unity_linux_UTSA-2025-680646.nasl

Version: 1.2

Type: local

Family: Unity Linux Local Security Checks

Published: 10/7/2025

Updated: 10/10/2025

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: Medium

Base Score: 6.8

Temporal Score: 5

Vector: CVSS2#AV:N/AC:M/Au:N/C:P/I:P/A:P

CVSS Score Source: CVE-2021-43860

CVSS v3

Risk Factor: High

Base Score: 8.6

Temporal Score: 7.5

Vector: CVSS:3.0/AV:L/AC:L/PR:N/UI:R/S:C/C:H/I:H/A:H

Temporal Vector: CVSS:3.0/E:U/RL:O/RC:C

Vulnerability Information

Required KB Items: Host/local_checks_enabled, Host/cpu, Host/UOS-Server/release, Host/UOS-Server/rpm-list

Exploit Ease: No known exploits are available

Patch Publication Date: 7/12/2025

Vulnerability Publication Date: 1/12/2022

Reference Information

CVE: CVE-2021-43860

Detections

Analytics