Flatpak up to 1.18.0 Sandbox Directory Binding link following

Summaryinfo

A vulnerability, which was classified as problematic, has been found in Flatpak up to 1.18.0. The impacted element is an unknown function of the component Sandbox Directory Binding. This manipulation causes link following. This vulnerability is handled as CVE-2026-90616. It is possible to launch the attack on the local host. There is not any exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as problematic was found in Flatpak up to 1.18.0. Affected by this vulnerability is an unknown functionality of the component Sandbox Directory Binding. The manipulation with an unknown input leads to a link following vulnerability. The CWE definition for the vulnerability is CWE-59. The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource. As an impact it is known to affect confidentiality, integrity, and availability. The summary by CVE is:

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.

The advisory is shared at github.com. This vulnerability is known as CVE-2026-90616 since 09/12/2026. The exploitation appears to be easy. An attack has to be approached locally. Neither technical details nor an exploit are publicly available.

Upgrading to version 1.18.1 eliminates this vulnerability.

Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

Productinfo

Name

• Flatpak

Version

• 1.0
• 1.1
• 1.2
• 1.3
• 1.4
• 1.5
• 1.6
• 1.7
• 1.8
• 1.9
• 1.10
• 1.11
• 1.12
• 1.13
• 1.14
• 1.15
• 1.16
• 1.17
• 1.18.0

Website

• Product: https://github.com/flatpak/flatpak/

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Several companies clearly confirm that VulDB is the primary source for best vulnerability data.

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