Answer in brief
CVE-2026-120307 records a Critical severity (CVSS 9.9) vulnerability in Beta9 container escape via unvalidated sandbox file paths. The current sources do not mark it as known exploited. The current feed maps beam-cloud/github.com/beam-cloud/beta9 (generic). Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.9. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps beam-cloud/github.com/beam-cloud/beta9 (generic). Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| beam-cloud/github.com/beam-cloud/beta9generic | >=0 <0.1.756 | 0.1.756 |
Published upstream
Nov 1, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Nov 1, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Nov 1, 2026
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.
Quoted source text, attributed separately from HOL analysis.