CVE-2026-49238
SFTP Server VM Escape in Canonical Multipass
Description
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.
INFO
Published Date :
May 28, 2026, 2:16 p.m.
Last Modified :
May 28, 2026, 4:16 p.m.
Remotely Exploit :
No
Source :
[email protected]
Affected Products
The following products are affected by CVE-2026-49238
vulnerability.
Even if cvefeed.io is aware of the exact versions of the
products
that
are
affected, the information is not represented in the table below.
No affected product recoded yet
CVSS Scores
| Score | Version | Severity | Vector | Exploitability Score | Impact Score | Source |
|---|---|---|---|---|---|---|
| CVSS 3.1 | HIGH | cc1ad9ee-3454-478d-9317-d3e869d708bc | ||||
| CVSS 3.1 | HIGH | [email protected] | ||||
| CVSS 3.1 | HIGH | MITRE-CVE |
Solution
- Update Canonical Multipass to version 1.16.3 or later.
- Apply vendor patches for SSHFS server component.
- Restrict guest VM access to host resources.
- Validate all path inputs rigorously.
References to Advisories, Solutions, and Tools
Here, you will find a curated list of external links that provide in-depth
information, practical solutions, and valuable tools related to
CVE-2026-49238.
| URL | Resource |
|---|---|
| https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w | |
| https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w |
CWE - Common Weakness Enumeration
While CVE identifies
specific instances of vulnerabilities, CWE categorizes the common flaws or
weaknesses that can lead to vulnerabilities. CVE-2026-49238 is
associated with the following CWEs:
Common Attack Pattern Enumeration and Classification (CAPEC)
Common Attack Pattern Enumeration and Classification
(CAPEC)
stores attack patterns, which are descriptions of the common attributes and
approaches employed by adversaries to exploit the CVE-2026-49238
weaknesses.
We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).
Results are limited to the first 15 repositories due to potential performance issues.
The following list is the news that have been mention
CVE-2026-49238 vulnerability anywhere in the article.
The following table lists the changes that have been made to the
CVE-2026-49238 vulnerability over time.
Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.
-
CVE Modified by 134c704f-9b21-4f2e-91b3-4a467353bcc0
May. 28, 2026
Action Type Old Value New Value Added Reference https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w -
New CVE Received by [email protected]
May. 28, 2026
Action Type Old Value New Value Added Description 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. Added CVSS V3.1 AV:L/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:N Added CWE CWE-22 Added Reference https://github.com/canonical/multipass/security/advisories/GHSA-rhp2-23c4-r34w