{"id":"CVE-2026-49238","title":"An issue was discovered in Canonical Multipass before version 1.16.3","summary":"An issue was discovered in Canonical Multipass before version 1.16.3. The host-side SFTP server component (sshfs_server), which executes with root privileges on the host, contains a path containment bypass vulnerability within its valida…","severity":"high","cvss":8.4,"cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N","cwe":["CWE-22"],"vendor":"canonical","product":"multipass","affected":["multipass < 1.16.3"],"patched":["multipass 1.16.3"],"published":"2026-05-28","updated":"2026-10-14","sourceUpdated":"2026-10-14T20:10:00.190","source":"NVD","sourceUrl":"https://nvd.nist.gov/vuln/detail/CVE-2026-49238","references":[{"url":"https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w","label":"security@ubuntu.com"},{"url":"https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w","label":"134c704f-9b21-4f2e-91b3-4a467353bcc0"}],"tags":["nvd"],"epss":0.00446,"epssPercentile":0.37238,"ingestedAt":"2026-10-14T20:53:12.337Z","slug":"CVE-2026-49238","body":"## Overview\n\nAn issue was discovered in Canonical Multipass before version 1.16.3. The host-side SFTP server component (sshfs_server), which executes with root privileges on the host, contains a path containment bypass vulnerability within its validate_path function in src/sshfs_mount/sftp_server.cpp. The function performs a plain string prefix comparison on requested paths without path separator validation or dot-dot (..) normalization. A local attacker with root privileges inside a guest virtual machine can bypass the FUSE layer by injecting raw SFTP frames (such as an SSH_FXP_OPEN request) directly into the sshfs_server process stdin/stdout pipes via procfs. By supplying a path containing directory traversal sequences that match the allowed mount prefix, the attacker can force the host-side root process to resolve the traversal and open files outside the designated mount boundary. This allows a guest-side user to read arbitrary files on the host filesystem, resulting in a virtual machine escape.\n\n## Affected\n\n- `multipass < 1.16.3`\n\n## Remediation\n\nUpgrade past the affected range:\n\n- `multipass 1.16.3`","depth":"twilight","depthScore":46,"depthScoreParts":{"impact":46.2,"likelihood":0.1,"exploitation":0,"ransomware":0},"changes":[]}