CVE-2026-49237: canonical multipass Incorrect Default Permissions

Vulnerability summary

CVE-2026-49237 is a high (CVSS 7.8) Incorrect Default Permissions vulnerability in canonical multipass. EPSS estimates a 0.16% chance of exploitation in the next 30 days, higher than 4.6% of scored vulnerabilities. 1 public exploit is recorded.

Timeline

1. 28-05-2026
   PublishedVulnerability first disclosed.
2. 28-05-2026
   Last modifiedVulnerability information updated.

Description

An issue was discovered in Canonical Multipass for macOS before version 1.16.3 due to an incomplete fix for CVE-2025-5199. While the patch in version 1.16.0 updated the ownership of the multipassd daemon binary to root:wheel, five co-located 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. Because the root LaunchDaemon (com.canonical.multipassd.plist) configures a PATH environment variable that prioritizes this user-writable directory and invokes these auxiliary binaries by their bare names, a local attacker can replace an auxiliary binary (such as qemu-img) with a malicious wrapper. When the root daemon subsequently triggers the binary during routine execution (e.g., via multipass launch), the malicious code executes with root privileges, leading to local privilege escalation.

• CWE-276Incorrect Default PermissionsDuring installation, installed file permissions are set to allow anyone to modify those files.