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CriticalVulnerabilityCVE-2026-120308updated 1 Nov 2026, 13:21 UTC

Beta9: tenants can reach other tenants' volumes on the worker machine

A customer with a normal login can reach files that belong to other customers on the same server, and can read and change them. The flaw comes from a missing check on which storage volume a deployment may attach.

Fix available · out Official source
SeverityCriticalCVSS 9.9 of 10
Being exploited?UnclearNo reports either way yet
Fix available?YesBeta9 gateway 0.1.776 and worker 0.1.756 · since 1 Nov 2026,
How sure is this?Official sourceBacked by an official source

How the attack works simplified

  1. 1Tenant with tokenHolds a valid workspace token
  2. 2Crafted volume IDIdentifier contains ../ segments, unchecked
  3. 3Path escapes rootGateway joins path to worker's filesystem root
  4. 4Read-write mountWorker mounts other tenants' files into sandbox
  5. ResultAttacker reads and writes other tenants' data

What happened

The Beta9 gateway builds a volume host path from the workspace name and an unvalidated volume identifier, so parent-directory segments (../) escape to the worker's filesystem root. The worker then bind-mounts that path read-write into the sandbox unless the volume is marked read-only.

Why it is dangerous: A tenant with a workspace token can read and write the worker's files, including other tenants' volumes stored on that machine. This affects multi-tenant Beta9 deployments.

Are you affected?

You are affected if you run Beta9 gateway 0.1.769 or worker 0.1.745 (confirmed affected builds), and tenants with workspace tokens can deploy functions, endpoints, or task queues with attached volumes.

Beta9 gateway 0.1.769 (confirmed); Beta9 worker 0.1.745 (confirmed). Other versions: unknown.

What to do

  1. Update the Beta9 gateway to 0.1.776 or later.
  2. Update the Beta9 worker to 0.1.756 or later.
  3. Confirm the fix covers existing stubs; the fix validates volume paths for stubs saved before the check existed.

Timeline

  1. 1 Nov 2026, 13:18 UTC
    Publicly disclosed
  2. 1 Nov 2026, 13:18 UTC
    Reported by NVD · NVD
  3. 1 Nov 2026, 13:21 UTC
    Picked up by Zero Radar

Sources 1 report, oldest first

Official vendor, government CERT or advisory database

Technical details

ID
CVE-2026-120308
CVSS
9.9 / 10
Disclosed
1 Nov 2026, 13:18 UTC
On Zero Radar
1 Nov 2026, 13:21 UTC (3 min after disclosure)
Last change
1 Nov 2026, 13:21 UTC

The plain-language parts and the attack diagram were written by an AI model (claude-haiku-5-5) from the sources above. Facts like versions, exploitation and dates come from the sources themselves. How Zero Radar works

Beta9: tenants can reach other tenants' volumes on the worker machine · Zero Radar