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CVE-2021-41133

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.

Published

2021-10-08T14:15:08.723

Last Modified

2024-11-21T06:25:33.023

Status

Modified

Source

[email protected]

Severity

CVSSv3.1: 8.8 (HIGH)

CVSSv2 Vector

AV:L/AC:L/Au:N/C:P/I:P/A:P

  • Access Vector: LOCAL
  • Access Complexity: LOW
  • Authentication: NONE
  • Confidentiality Impact: PARTIAL
  • Integrity Impact: PARTIAL
  • Availability Impact: PARTIAL
Exploitability Score

3.9

Impact Score

6.4

Weaknesses
  • Type: Secondary
    CWE-20
  • Type: Primary
    NVD-CWE-Other
Affected Vendors & Products
Type Vendor Product Version/Range Vulnerable?
Application flatpak flatpak < 1.8.2 Yes
Application flatpak flatpak < 1.10.4 Yes
Application flatpak flatpak < 1.12.1 Yes
Operating System debian debian_linux 11.0 Yes
Operating System fedoraproject fedora 33 Yes
Operating System fedoraproject fedora 34 Yes
References