VM escape via unnormalized SFTP paths
Published May 28, 2026 · Updated May 28, 2026
Path traversal in Canonical Multipass before 1.16.3 allows guest OS users with root access to read arbitrary host files via SFTP mounts. Host-side sshfs_server validate_path compares raw path prefixes without separator checks or dot-dot normalization before opening the resolved path as root. Exploitation requires root inside a guest and an existing host-directory mount; the published proof of concept was confirmed only on macOS.
Summary
What happened
Path traversal in Canonical Multipass before 1.16.3 allows guest OS users with root access to read arbitrary host files via SFTP mounts. Host-side sshfs_server validate_path compares raw path prefixes without separator checks or dot-dot normalization before opening the resolved path as root. Exploitation requires root inside a guest and an existing host-directory mount; the published proof of concept was confirmed only on macOS.
The record
- CVE
- CVE-2026-49238
- Published
- May 28, 2026
- Updated
- May 28, 2026
- Vendor
- Canonical
- Product
- Multipass
- Classifications
- CWE-22, T1005
- Attack vector
- local
- Privileges
- admin
Timeline
How it unfolded
- May 28, 2026CVE publishedPublication date reported by the CVE source.
- May 28, 2026Record updatedLatest update available in the CVE record.
Exploitability
Present is not the same as exploitable
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Is a vulnerable build present?
Compare these published version ranges with your installed build and any vendor patches.
- Affected versionversion=0 <1.16.3
What conditions does exploitation require?
What is affected?
Published CVSS scores
CVSS describes severity. EPSS estimates exploitation probability.
Attacks
What attackers are doing with it
Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.
Weakness, pattern, technique
Public exploit references
- Canonical advisory SFTP pipe-injection proof of conceptfunctional · demonstrated
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Technologies
Your stack
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Your stack
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