Beta9: Build worker isolation deficiency (CVE-2026-120306)
Beta9 worker pods execute tenant image definition shell commands with inadequate isolation, allowing access to the worker's filesystem and privileged resources.
CVE search metadata
CVE search record: CVE-2026-120306. Severity: critical. CVSS: 9.9. KEV: no. Product: Beta9 worker (prior to 0.1.756). Brief: Beta9: Build worker isolation deficiency (CVE-2026-120306). Brief link: https://feed.craftedsignal.io/briefs/2026-11-beta9-worker-breakout/
Triage facts
Revision 1- Applicability
- Beta9 worker (prior to 0.1.756)
- Evidence
- Unknown
- Severity
- Critical
- Sources
- 1 public source
- Freshness
- Revision 1Nov 1, 14:53 UTC
- Vulnerabilities
- 1 CVE
- Source quality
- A2Roughly even chance
Beta9 worker pods perform image builds using Buildah with insufficient isolation. Tenant-provided shell commands are executed as RUN instructions within the worker, which shares PID, network, IPC, and user namespaces with the build worker container. The worker runs as UID 0 with CAP_DAC_OVERRIDE. Access to /proc/1/root allows the build process to interact with the worker's filesystem, which contains runc, buildah, and runsc binaries, Kubernetes service account tokens, and mounted host directories.