CVE-2021-41133 : Security Advisory and Response

A vulnerability in Flatpak versions prior to 1.10.4 and 1.12.0 allows sandbox bypass via VFS-manipulating syscalls, potentially leading to privilege escalation.

Understanding CVE-2021-41133

What is CVE-2021-41133?

Flatpak, a tool for sandboxing desktop applications on Linux, is affected by a vulnerability where manipulating VFS via specific syscalls can deceive the system into treating sandboxes as non-sandboxed processes.

The Impact of CVE-2021-41133

The vulnerability enables Flatpak apps to elevate privileges by tricking host-OS services, posing a risk of unauthorized access and manipulation beyond their intended boundaries.

Technical Details of CVE-2021-41133

Vulnerability Description

Flatpak apps can abuse recent mount-related syscalls to manipulate VFS, bypassing Flatpak's seccomp filter and impersonating non-sandboxed processes.

Affected Systems and Versions

flatpak versions 1.8.0 to 1.8.2
flatpak versions 1.10.0 to 1.10.4
flatpak versions 1.11.0 to 1.12.0

Exploitation Mechanism

Exploitation involves accessing AF_UNIX sockets used by Wayland, Pipewire, or pipewire-pulse to escalate the app's privileges.

Mitigation and Prevention

Immediate Steps to Take

Update Flatpak to the patched versions (1.10.4 and 1.12.0) to mitigate the vulnerability effectively.

Long-Term Security Practices

Regularly monitor and apply security patches for all software components to prevent future vulnerabilities.

Patching and Updates

Ensure timely application of security patches and updates to all system components to address known security issues.