CVE-2026-49238

{"id": "CVE-2026-49238", "cveTags": [], "metrics": {"cvssMetricV31": [{"type": "Secondary", "source": "security@ubuntu.com", "cvssData": {"scope": "CHANGED", "version": "3.1", "baseScore": 8.4, "attackVector": "LOCAL", "baseSeverity": "HIGH", "vectorString": "CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N", "integrityImpact": "HIGH", "userInteraction": "NONE", "attackComplexity": "LOW", "availabilityImpact": "NONE", "privilegesRequired": "LOW", "confidentialityImpact": "HIGH"}, "impactScore": 5.8, "exploitabilityScore": 2.0}]}, "published": "2026-05-28T14:16:24.403", "references": [{"url": "https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w", "tags": ["Third Party Advisory", "Exploit"], "source": "security@ubuntu.com"}, {"url": "https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w", "tags": ["Third Party Advisory", "Exploit"], "source": "134c704f-9b21-4f2e-91b3-4a467353bcc0"}], "vulnStatus": "Analyzed", "weaknesses": [{"type": "Secondary", "source": "security@ubuntu.com", "description": [{"lang": "en", "value": "CWE-22"}]}], "descriptions": [{"lang": "en", "value": "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 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."}], "lastModified": "2026-06-01T13:26:31.580", "configurations": [{"nodes": [{"negate": false, "cpeMatch": [{"criteria": "cpe:2.3:a:canonical:multipass:*:*:*:*:*:*:*:*", "vulnerable": true, "matchCriteriaId": "633AA429-4296-43D2-8F9F-D5115F121BD3", "versionEndExcluding": "1.16.3"}], "operator": "OR"}]}], "sourceIdentifier": "security@ubuntu.com"}