Description
In Flatpak before 1.18.1, a malicious sandboxed app can obtain arbitrary read and write access to files on the host, which can be escalated to arbitrary code execution on the host, a different vulnerability than CVE-2026-76925. Flatpak creates a few app data directories (e.g., /var/cache, /var/data, /var/config, and /var/tmp) in every sandbox on every app launch where, in some cases, components of the path are attacker-controlled. Missing symlink protection can redirect the directories. Some of these directories are bind-mounted by Flatpak by passing the path (e.g., /home/user/.var/app/APP_ID/cache/tmp), which contains attacker-controlled directories (tmp) to bwrap --bind SRC DST. bwrap passes the path on to the kernel, which then follows symlinks. A malicious symlink can point to arbitrary locations on the host and it will become mounted inside the sandbox.
Published: 2026-09-12
Score: 7.4 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Solution

https://github.com/flatpak/flatpak/commit/478072972056d2d15c768c246f80abdf83cf0e5e

Tracking

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Advisories

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History

Sat, 12 Sep 2026 20:15:00 +0000

Type Values Removed Values Added
Description In Flatpak before 1.18.1, a malicious sandboxed app can obtain arbitrary read and write access to files on the host, which can be escalated to arbitrary code execution on the host, a different vulnerability than CVE-2026-76925. Flatpak creates a few app data directories (e.g., /var/cache, /var/data, /var/config, and /var/tmp) in every sandbox on every app launch where, in some cases, components of the path are attacker-controlled. Missing symlink protection can redirect the directories. Some of these directories are bind-mounted by Flatpak by passing the path (e.g., /home/user/.var/app/APP_ID/cache/tmp), which contains attacker-controlled directories (tmp) to bwrap --bind SRC DST. bwrap passes the path on to the kernel, which then follows symlinks. A malicious symlink can point to arbitrary locations on the host and it will become mounted inside the sandbox.
First Time appeared Flatpak
Flatpak flatpak
Weaknesses CWE-61
CPEs cpe:2.3:a:flatpak:flatpak:*:*:*:*:*:*:*:*
Vendors & Products Flatpak
Flatpak flatpak
References
Metrics cvssV3_1

{'score': 7.4, 'vector': 'CVSS:3.1/AV:L/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: mitre

Published:

Updated: 2026-09-12T20:00:58.476Z

Reserved: 2026-09-12T20:00:58.046Z

Link: CVE-2026-90616

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-09-12T20:16:30.957

Modified: 2026-09-12T20:16:30.957

Link: CVE-2026-90616

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

No data.

Weaknesses