PT-2026-44376 · Canonical · Multipass

Espreto · Published 2026-05-28 · Updated 2026-06-23 · CVE-2026-49238

Positive Technologies (AI Summary)

CVSS v3.1

8.4

High

Base vector

AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N

Name of the Vulnerable Software and Affected Versions Canonical Multipass versions prior to 1.16.3

Description The host-side SFTP server component (sshfs server), which runs with root privileges on the host, contains a path containment bypass in the validate path() function. This function uses a plain string prefix comparison for requested paths but fails to perform path separator validation or dot-dot (..) normalization. A local attacker with root privileges inside a guest virtual machine can bypass the FUSE (Filesystem in Userspace) layer—a mechanism that allows non-privileged users to create their own file systems—by injecting raw SFTP frames, such as an SSH FXP OPEN request, directly into the sshfs server process pipes via procfs. By using directory traversal sequences that match the allowed mount prefix, the attacker can force the host process to open files outside the designated boundary, enabling the reading of arbitrary files on the host filesystem and resulting in a virtual machine escape.

Recommendations Update to version 1.16.3 or later.

Exploit

Fix

Path traversal

Weakness Enumeration

CWE-22

Related Identifiers

CVE-2026-49238

GHSA-RHP2-23C4-R34W

Affected Products

Multipass

References · 6

• 🔥 https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w · Exploit
• 🔥 https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/49xxx/CVE-2026-49238.json · Exploit
• https://osv.dev/vulnerability/CVE-2026-49238 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-49238 · Security Note
• https://twitter.com/espreto/status/2069503458701685040 · Twitter Post
• https://t.me/cveNotify/165051 · Telegram Post