CVE-2026-120307
Received Received - Intake

Path Traversal in Beta9 Worker Sandbox

Vulnerability report for CVE-2026-120307, including description, CVSS score, EPSS score, affected products, exploitability, helpful resources, and attack-flow context.

Publication date: 2026-11-01

Last updated on: 2026-11-01

Assigner: JFrog

Description

The Beta9 worker serves the sandbox file API from outside the container. getHostPathFromContainerPath turns the tenant's container path into a worker path. If the unresolved path starts with a mount destination, including the default upload mount at /tmp/.beta9, the remainder is joined onto that mount's source with filepath.Join, which cleans parent-directory segments after the prefix check. A long enough run of those segments names any absolute path on the worker. A path that matches no mount is joined onto the container root and opened in the worker's own filesystem, so an absolute symbolic link such as /var/run pointing at /run is followed against the worker root. Upload, download, stat, list, find-in-files, replace-in-files, and delete-file all call this helper. A tenant with a workspace token and one running sandbox can read, write, list, and delete files on the hosting worker as root, including files of other tenants on that machine. A read-only proof downloaded the worker pod's Kubernetes service account token through the file API for a path that did not exist inside the sandbox. In the shipped remote-node manifests that service account is bound to cluster-admin. Fixed in worker 0.1.756: sandbox file operations and workspace sync open paths with os.OpenRoot, so parent-directory and symlink lookups stay inside the container root or the mount source.

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Meta Information

Published
2026-11-01
Last Modified
2026-11-01
Generated
2026-11-01
AI Q&A
2026-11-01
EPSS Evaluated
N/A
NVD

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
beam-cloud Beta9 worker 0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-22 The product uses external input to construct a pathname that is intended to identify a file or directory that is located underneath a restricted parent directory, but the product does not properly neutralize special elements within the pathname that can cause the pathname to resolve to a location that is outside of the restricted directory.
CWE-23 The product uses external input to construct a pathname that should be within a restricted directory, but it does not properly neutralize sequences such as ".." that can resolve to a location that is outside of that directory.
CWE-59 The product attempts to access a file based on the filename, but it does not properly prevent that filename from identifying a link or shortcut that resolves to an unintended resource.

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Executive Summary

This vulnerability allows a tenant with a workspace token and running sandbox to escape the container and access files on the hosting worker as root. It exploits path traversal and symlink following in sandbox file APIs to read, write, list, or delete files outside the intended container environment. The issue was fixed in worker version 0.1.756 by confining file operations to scoped roots using os.OpenRoot.

Detection Guidance

This vulnerability allows tenants to read, write, list, and delete files on the hosting worker as root, including files of other tenants. Detection requires checking for unauthorized file access or modifications in the Beta9 worker filesystem. Review logs for suspicious file operations in /tmp/.beta9 or /var/run paths. Check for unexpected symlinks or path traversals in sandbox file APIs. Verify worker version is not vulnerable (fixed in worker 0.1.756).

Impact Analysis

An attacker could access sensitive files on the worker, including Kubernetes service account tokens with cluster-admin privileges. They could also modify or delete critical files, potentially affecting other tenants on the same machine. The impact includes unauthorized data access, system compromise, and disruption of services.

Compliance Impact

This vulnerability could lead to unauthorized access to personal or sensitive data, violating GDPR's data protection principles and HIPAA's security requirements. It may result in data breaches, non-compliance penalties, and loss of trust in systems handling regulated data.

Mitigation Strategies

Upgrade the Beta9 worker to version 0.1.756 or later immediately. Ensure sandbox file operations and workspace sync use os.OpenRoot to confine paths. Validate volume IDs and mount paths before mounting. Restrict workspace ownership checks and enforce read-only mounts where applicable. Disable external tools like ripgrep in worker images.

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