Beam Cloud gateway/worker Volume Identifier Validation path traversal

Summaryinfo

A vulnerability was found in Beam Cloud gateway and worker. It has been classified as very critical. This affects an unknown part of the component Volume Identifier Validation. Performing a manipulation results in path traversal. This vulnerability is identified as CVE-2026-120308. The attack can be initiated remotely. There is not any exploit available.

Detailsinfo

A vulnerability classified as very critical has been found in Beam Cloud gateway and worker (unknown version). This affects an unknown code block of the component Volume Identifier Validation. The manipulation with an unknown input leads to a path traversal vulnerability. CWE is classifying the issue as 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. This is going to have an impact on confidentiality, integrity, and availability. The summary by CVE is:

A Beta9 tenant can attach a volume when deploying a function, endpoint, or task queue. The gateway builds the host path by joining the shared volumes root, the workspace name, and the volume identifier from the stub configuration. Nothing checks that the identifier names a volume that workspace owns. Parent-directory segments in the identifier collapse the joined path to the worker's filesystem root, and the worker bind-mounts that path into the sandbox read-write unless the volume was explicitly marked read-only. A tenant with a workspace token can therefore read and write the worker's files, including other tenants' volumes stored on that machine. Confirmed against gateway 0.1.769 and worker 0.1.745. Fixed in gateway 0.1.776 and worker 0.1.756: volume identifiers and mount paths are validated before a mount is built, including for stubs saved before the check existed, and the gateway rejects a volume that does not exist or is not owned by the workspace.

It is possible to read the advisory at github.com. This vulnerability is uniquely identified as CVE-2026-120308 since 11/01/2026. The exploitability is told to be easy. It is possible to initiate the attack remotely. The technical details are unknown and an exploit is not publicly available. The pricing for an exploit might be around USD $0-$5k at the moment (estimation calculated on 11/01/2026). The attack technique deployed by this issue is T1006 according to MITRE ATT&CK.

There is no information about possible countermeasures known. It may be suggested to replace the affected object with an alternative product.

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Productinfo

Type

• Cloud Software

Vendor

• Beam Cloud

Name

• gateway
• worker

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CPE 2.2info

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