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Amazon Linux 2 : flatpak, --advisory ALAS2-2026-3261 (ALAS-2026-3261)

critical Nessus Plugin ID 311225

Synopsis

The remote Amazon Linux 2 host is missing a security update.

Description

The version of flatpak installed on the remote host is prior to 1.0.9-10. It is, therefore, affected by a vulnerability as referenced in the ALAS2-2026-3261 advisory.

 A complete sandbox escape vulnerability exists in Flatpak before 1.16.4. The Flatpak portal accepts paths in the sandbox-expose options which can be app-controlled symlinks pointing at arbitrary paths. Flatpak run mounts the resolved host path in the sandbox, giving apps access to all host files and enabling code execution in the host context. (CVE-2026-34078)

Tenable has extracted the preceding description block directly from the tested product 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

Run 'yum update flatpak' or or 'yum update --advisory ALAS2-2026-3261' to update your system.

See Also

https://alas.aws.amazon.com//AL2/ALAS2-2026-3261.html

https://alas.aws.amazon.com/faqs.html

https://explore.alas.aws.amazon.com/CVE-2026-34078.html

Plugin Details

Severity: Critical

ID: 311225

File Name: al2_ALAS-2026-3261.nasl

Version: 1.1

Type: Local

Agent: unix

Published: 4/30/2026

Updated: 4/30/2026

Supported Sensors: Nessus Agent, Continuous Assessment, Nessus

Risk Information

VPR

Risk Factor: High

Score: 7.3

CVSS v2

Risk Factor: Critical

Base Score: 10

Temporal Score: 7.4

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

CVSS Score Source: CVE-2026-34078

CVSS v3

Risk Factor: Critical

Base Score: 10

Temporal Score: 8.7

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

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

CVSS v4

Risk Factor: Critical

Base Score: 9.3

Threat Score: 8.1

Threat Vector: CVSS:4.0/E:U

Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

Vulnerability Information

CPE: p-cpe:/a:amazon:linux:flatpak-debuginfo, p-cpe:/a:amazon:linux:flatpak-devel, cpe:/o:amazon:linux:2, p-cpe:/a:amazon:linux:flatpak-libs, p-cpe:/a:amazon:linux:flatpak, p-cpe:/a:amazon:linux:flatpak-builder

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

Exploit Ease: No known exploits are available

Patch Publication Date: 4/30/2026

Vulnerability Publication Date: 4/7/2026

Reference Information

CVE: CVE-2026-34078

IAVA: 2026-A-0317