{"cve":"CVE-2026-120306","nvd":{"published":"2026-11-01T13:18:01.300","modified":"2026-11-01T13:18:01.300","status":"Received","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.","cvss_v4":null,"cvss_v3":{"version":"3.1","vector":"CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:C/C:H/I:H/A:H","score":9.9},"cwes":["CWE-269","CWE-653"],"references":["https://github.com/beam-cloud/beta9","https://github.com/beam-cloud/beta9/commit/a28bf12cf0007c792a25d8ed282b4e8bf6f30393","https://github.com/beam-cloud/beta9/pull/1897","https://github.com/beam-cloud/beta9/releases/tag/worker-0.1.756"],"reference_tags":[{"url":"https://github.com/beam-cloud/beta9","tags":[]},{"url":"https://github.com/beam-cloud/beta9/commit/a28bf12cf0007c792a25d8ed282b4e8bf6f30393","tags":[]},{"url":"https://github.com/beam-cloud/beta9/pull/1897","tags":[]},{"url":"https://github.com/beam-cloud/beta9/releases/tag/worker-0.1.756","tags":[]}],"products":[],"affected":[],"source":"nvd","synced_at":"2026-11-01T13:45:47.480843424+00:00"},"epss":null,"kev":null,"exploits":[],"weaknesses":[{"name":"Improper Privilege Management","common_name":null,"deprecated":false,"replaced_by":[],"id":"CWE-269"},{"name":"Improper Isolation or Compartmentalization","common_name":null,"deprecated":false,"replaced_by":[],"id":"CWE-653"}],"osv":[],"fixed":[],"attribution":["This product uses the NVD API but is not endorsed or certified by the NVD.","EPSS scores: FIRST Exploit Prediction Scoring System, https://www.first.org/epss","Known exploited vulnerabilities: CISA Known Exploited Vulnerabilities Catalog, https://www.cisa.gov/known-exploited-vulnerabilities-catalog","Package advisories: OSV (https://osv.dev), from the GitHub Advisory Database, PyPA, Go, RustSec and other ecosystem databases, under CC-BY 4.0 or CC0","CVE records: the CVE Program's CVE List (https://www.cve.org), under its terms of use (https://www.cve.org/Legal/TermsOfUse). CVE is a registered trademark of The MITRE Corporation; this product is not affiliated with the CVE Program.","Public exploits: links to the Exploit Database (https://www.exploit-db.com, by OffSec; index under GPL-2.0), Rapid7's Metasploit Framework modules (https://github.com/rapid7/metasploit-framework, BSD-3-Clause) and ProjectDiscovery's nuclei templates (https://github.com/projectdiscovery/nuclei-templates, MIT). Only the links, titles and dates are stored; no exploit code is fetched or served.","CWE names and descriptions: MITRE's Common Weakness Enumeration (https://cwe.mitre.org), Copyright © 2006–2026, The MITRE Corporation, under the CWE terms of use (https://cwe.mitre.org/about/termsofuse.html). CWE is a trademark of The MITRE Corporation."]}