Beta9 container escape via unvalidated sandbox file paths
Default status is the baseline for the product, each version can override it (e.g. patched versions marked unaffected).
| Vendor | Product | Default status | Versions | ||||||
|---|---|---|---|---|---|---|---|---|---|
| beam-cloud | Beta9 worker | unaffected |
|
No data.
No data.
| Vendor | Product | Versions | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Beam-cloud | Beta9 |
|
Vendor Solution
Upgrade the Beta9 worker to 0.1.756 or later. Sandbox file APIs and workspace sync use os.OpenRoot, so parent-directory segments and symbolic links stay inside the container root or the mount source. File operations refuse read-only mounts and do not write through a symlink swapped in after path resolution. The fix is commit a28bf12 (pull request 1897), released as worker-0.1.756 on 2026-09-15.
No CVSS v4.0
No CVSS v3.0
No CVSS v2
This CVE is not in the KEV list.
Exploit prediction score: < 1% (0.484% probability within 30 days)
| Type | Values Removed | Values Added |
|---|---|---|
| First Time appeared |
Beam-cloud
Beam-cloud beta9 |
|
| Vendors & Products |
Beam-cloud
Beam-cloud beta9 |
| Type | Values Removed | Values Added |
|---|---|---|
| Metrics |
ssvc
|
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Title | Beta9 container escape via unvalidated sandbox file paths | |
| Weaknesses | CWE-22 CWE-23 CWE-59 |
|
| References |
| |
| Metrics |
cvssV3_1
|