Creation of Temporary File With Insecure Permissions in Flatpak - CVE-2026-97026

Vulnerability identifier: #VU152569

CSH Severity: Low

CVSS v4: 4.6 [CVSS:4.0/AV:L/AC:L/AT:N/PR:N/UI:A/VC:L/VI:N/VA:L/SC:N/SI:N/SA:N]

CVE-ID: CVE-2026-97026

CWE-ID: CWE-378

Exploitation vector: Local access

Exploit availability: No public exploit available

The vulnerability allows a local user to cause a denial of service.

The vulnerability exists due to insecure temporary directory permissions in temporary child repositories under the system-helper cache path when installing apps. A local user can modify the temporary directory to cause a denial of service.

Exploitation is limited to multi-user systems where the user's umask permits other users to write to the cache directory.

Flatpak
Debian Linux
Anolis OS
flatpak
flatpak-devel
flatpak-libs
flatpak-session-helper
flatpak-tests
flatpak-doc
flatpak-selinux
flatpak (Debian package)

Install security update from vendor's website.

Flatpak - update to 1.18.4
flatpak - update to 1.18.4-1
flatpak-devel - update to 1.18.4-1
flatpak-libs - update to 1.18.4-1
flatpak-session-helper - update to 1.18.4-1
flatpak-tests - update to 1.18.4-1
flatpak-doc - update to 1.18.4-1
flatpak-selinux - update to 1.18.4-1
flatpak (Debian package) - update to 1.16.6-1~deb13u3

• https://github.com/flatpak/flatpak/security/advisories/GHSA-r9w3-qx54-qvc8
• https://github.com/flatpak/flatpak/commit/011dfae2f76d27d7e148c575dca5309a3cb4c852

• Multiple vulnerabilities in Flatpak
• Anolis OS update for flatpak
• Debian update for flatpak