CVE-2021-41133 Information

Jun 07, 2022 cve

Description

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 Flatpak’s 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.

CVSS Vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Reference

Attack Complexity

LOW

Privileges Required

LOW

User Interaction Required

LOW

Scope

NONE

Confidentiality Impact

UNCHANGED

Integrity Impact

HIGH

Availability Impact

HIGH

Base Score

HIGH

Base Severity

7.8

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