Executive brief
Canonical Multipass is a tool used to run and manage Ubuntu virtual machines on macOS. A security flaw allows a local user who installed the software to gain full administrative (root) control over the computer. By replacing certain helper files with malicious versions, an attacker can trick the background service into running unauthorized code with the highest possible system privileges.
Technical details
This vulnerability is an incomplete fix for CVE-2025-5199. While the main 'multipassd' daemon binary was secured in version 1.16.0, five auxiliary binaries (multipass, qemu-img, qemu-system-aarch64, qemu-system-x86_64, and sshfs_server) in '/Library/Application Support/com.canonical.multipass/bin/' retain ownership by the installing user and remain writable. The root LaunchDaemon (com.canonical.multipassd.plist) configures a PATH environment variable that prioritizes this user-writable directory and invokes these binaries by their bare names. A local attacker can replace one of these binaries, such as 'qemu-img', with a malicious wrapper. When the root daemon triggers the binary during routine operations like 'multipass launch', the malicious code executes with root privileges. The issue is patched in version 1.16.3.
Affected products
- Canonical Multipass before 1.16.3
Timeline
- 2026-05-28: advisory: Canonical published security advisory GHSA-r2xg-x32f-23c5
- 2026-05-28: disclosed: CVE-2026-49237 published to NVD