CVE-2026-120306
Received Received - Intake

Privilege Escalation in Beta9 Worker Pod

Publication date: 2026-11-01

Last updated on: 2026-11-01

Assigner: JFrog

Description
Beta9 turns each shell command in a tenant image definition into a Dockerfile RUN line and executes it with Buildah on the build worker. The worker image sets BUILDAH_ISOLATION=chroot, and no buildah invocation passes --isolation, so the step only changes its filesystem root. It keeps the worker pod's PID, network, IPC, and user namespaces, runs as uid 0, and holds CAP_DAC_OVERRIDE. PID 1 in that procfs is the worker entrypoint, so /proc/1/root is the worker container's filesystem and is writable. That filesystem contains the runc, buildah, and runsc binaries the worker uses to start tenant containers, the worker's Kubernetes service account token, and the host directories mounted into the pod. Worker pods are privileged. Clip v2 layered builds are the default, so a tenant with a workspace token reaches this by submitting one image build. The read-only proof confirmed the shared namespaces, CAP_DAC_OVERRIDE, and that the worker's runc binary is visible at /proc/1/root. Fixed in worker 0.1.756: Buildah RUN steps, including the WORKDIR mkdir, use OCI isolation with private PID, IPC, and network namespaces, and tenant ARG values are passed only into the build container.

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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
CVE-2026-120306

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-269 The product does not properly assign, modify, track, or check privileges for an actor, creating an unintended sphere of control for that actor.
CWE-653 The product does not properly compartmentalize or isolate functionality, processes, or resources that require different privilege levels, rights, or permissions.

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Executive Summary

This vulnerability allows a tenant with a workspace token to escape the build container isolation in Beta9 by submitting an image build. The worker pod runs with privileged access and shared namespaces, enabling modification of critical host binaries and files like runc, buildah, and Kubernetes service account tokens. The attacker can gain control over the host system through this container escape.

Impact Analysis

If exploited, this vulnerability could allow an attacker to gain root access on the host system, compromise other tenant workloads, steal sensitive data like Kubernetes tokens, or escalate attacks to the broader cluster infrastructure. It undermines the isolation guarantees of the Beta9 platform.

Compliance Impact

This vulnerability severely impacts compliance by enabling unauthorized access to sensitive data and host systems. It violates principles of least privilege and data segregation required by GDPR and HIPAA, potentially leading to data breaches and regulatory penalties due to insufficient container isolation.

Mitigation Strategies

Update the Beta9 worker image to version 0.1.756 or later to enable OCI isolation with private namespaces for Buildah RUN steps.

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