Flatpak is a system for building, distributing, and running sandboxed desktop applications on Linux. In versions prior to 1.10.4 and 1.12.0, Flatpak apps with direct access to AF_UNIX sockets such as those used by Wayland, Pipewire or pipewire-pulse can trick portals and other host-OS services into treating the Flatpak app as though it was an ordinary, non-sandboxed host-OS process. They can do this by manipulating the VFS using recent mount-related syscalls that are not blocked by Flatpaks denylist seccomp filter, in order to substitute a crafted /.flatpak-info or make that file disappear entirely. Flatpak apps that act as clients for AF_UNIX sockets such as those used by Wayland, Pipewire or pipewire-pulse can escalate the privileges that the corresponding services will believe the Flatpak app has. Note that protocols that operate entirely over the D-Bus session bus (user bus), system bus or accessibility bus are not affected by this. This is due to the use of a proxy process xdg-dbus-proxy, whose VFS cannot be manipulated by the Flatpak app, when interacting with these buses. Patches exist for versions 1.10.4 and 1.12.0, and as of time of publication, a patch for version 1.8.2 is being planned. There are no workarounds aside from upgrading to a patched version.
| Name | Vendor | Start Version | End Version |
|---|---|---|---|
| Flatpak | Flatpak | * | 1.8.2 (excluding) |
| Flatpak | Flatpak | 1.10.0 (including) | 1.10.4 (excluding) |
| Flatpak | Flatpak | 1.11.1 (including) | 1.12.1 (excluding) |
| Flatpak | Ubuntu | bionic | * |
| Flatpak | Ubuntu | focal | * |
| Flatpak | Ubuntu | hirsute | * |
| Flatpak | Ubuntu | impish | * |
| Flatpak | Ubuntu | trusty | * |
| Flatpak | Ubuntu | upstream | * |
| Flatpak | Ubuntu | xenial | * |
| Red Hat Enterprise Linux 7 | RedHat | flatpak-0:1.0.9-12.el7_9 | * |
| Red Hat Enterprise Linux 8 | RedHat | flatpak-0:1.8.5-4.el8_4 | * |
| Red Hat Enterprise Linux 8.1 Extended Update Support | RedHat | flatpak-0:1.0.9-5.el8_1 | * |
| Red Hat Enterprise Linux 8.2 Extended Update Support | RedHat | flatpak-0:1.6.2-6.el8_2 | * |