OESA-2026-4569: flatpak security update
flatpak is a system for building, distributing and running sandboxed desktop applications on Linux. See https://wiki.gnome.org/Projects/SandboxedApps for more information. Security Fix(es):
In Flatpak before 1.18.1, the revokefs writer, used by the flatpak-system-helper to receive repository data from unprivileged callers, validated file paths by rejecting literal .. components but did not prevent symlink traversal. A malicious local user in an active local session could obtain two revokefs sessions via the system helper, create a symlink in one session pointing into the other session's directory, and retain a file descriptor through that symlink. This allowed the attacker to modify files belonging to a different revokefs session after they had been validated and imported by the system helper. In particular, an attacker could use this to tamper with ostree commit objects in the system repository after they passed signature verification, enabling root-controlled file writes to attacker-chosen paths and local root privilege escalation.(CVE-2026-96808)
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
Upgrade
openeuler/flatpakto a version that resolves this vulnerability.Fixed in 1.10.2-16.oe2203sp4 - Upgrade
Upgrade
flatpakto a version that resolves this vulnerability.Fixed in 1.18.1
Event History
Frequently Asked Questions
Who can realistically exploit this issue?
A malicious local user with an active local session can exploit it. The issue does not require prior privileges or user interaction, but exploitation has high attack complexity.
What does an attacker need to do to exploit it?
The attacker needs to obtain two revokefs sessions through the system helper, create a symlink from one session into the other session's directory, and retain a file descriptor through that symlink. This can allow modification of repository data after it has been validated and imported.
What is the potential impact of successful exploitation?
An attacker can tamper with ostree commit objects after signature verification. This can lead to root-controlled writes to attacker-chosen paths and local root privilege escalation.
Which Flatpak versions are affected?
Flatpak versions before 1.18.1 are affected.