Alibaba Cloud Linux 3 : 0023: flatpak (ALINUX3-SA-2021:0023)

high Nessus Plugin ID 236596

Synopsis

The remote Alibaba Cloud Linux host is missing one or more security updates.

Description

The remote Alibaba Cloud Linux 3 host has packages installed that are affected by a vulnerability as referenced in the ALINUX3-SA-2021:0023 advisory.

Package updates are available for Alibaba Cloud Linux 3 that fix the following vulnerabilities:

CVE-2021-21381:
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`.

Tenable has extracted the preceding description block directly from the Alibaba Cloud 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 packages.

Plugin Details

Severity: High

ID: 236596

File Name: alinux3_sa_2021-0023.nasl

Version: 1.1

Type: local

Family: Alibaba Cloud Linux Local Security Checks

Published: 5/14/2025

Updated: 5/14/2025

Supported Sensors: Nessus

Risk Information

VPR

Risk Factor: Medium

Score: 6.3

CVSS v2

Risk Factor: Medium

Base Score: 5.8

Temporal Score: 4.3

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

CVSS Score Source: CVE-2021-21381

CVSS v3

Risk Factor: High

Base Score: 8.2

Temporal Score: 7.1

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

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

Vulnerability Information

CPE: cpe:/o:alibabacloud:alibaba_cloud_linux_3, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-tests, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-debugsource, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-selinux, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-tests-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-libs-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-session-helper, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-session-helper-debuginfo, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-devel, p-cpe:/a:alibabacloud:alibaba_cloud_linux_3:flatpak-libs

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

Exploit Ease: No known exploits are available

Patch Publication Date: 4/7/2021

Vulnerability Publication Date: 3/10/2021

Reference Information

CVE: CVE-2021-21381

Detections

Analytics