Heym Unsandboxed skill code execution: skills run via a local backend subprocess without the Docker isolation that Python tools mandate

published 2026-07-11 4mo ago modified 2026-11-11 12h ago also GHSA-hcv7-mg77-pg73 , EUVD-2026-124044

Unreviewed: the maintainers' own advisory

Published by the maintainers on their GitHub repository heymrun/heym. GitHub has not reviewed it into the GitHub Advisory Database, so the affected packages and versions are the maintainers' word. Read the full advisory on GitHub.

cvss: 8.8; version 3.1, CNA
cisa kev: Not listed; not in CISA's catalog
epss: —; no EPSS score yet
public exploits: 0; none known

Heym builds and runs agentic systems and business-process automations on self-hosted infrastructure. Prior to version 0.0.70, heym hardens one untrusted-code path but not its sibling. The Python tool executor (python_tool_executor.py) treats user code as untrusted and mandates a Docker sandbox (no network, read-only fs, non-root, no docker socket), failing closed. The skill executor (skill_python_executor.py) runs skill Python via a local backend subprocess with no Docker isolation — only a 512 MB RLIMIT and a 7-key env denylist — so a skill executes inside the backend execution context, with filesystem access, network egress, and non-denylisted environment variables that should not be exposed to untrusted/shared skills. In the shipped Docker config (backend runs as root + /var/run/docker.sock mounted), this escalates to host root. This issue has been patched in version 0.0.70.

Patch / fix

links 3

github.com/heymrun/heym@2155057 commit
github.com/heymrun/heym@28bb290 commit
github.com/heymrun/heym/releases/tag/0.0.70 release

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CVSS scores

assigned by	version	score	vector
CNA	3.1	8.8	CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Affected products

heymrun heym

Classification

Weakness

CWE-94 Improper Control of Generation of Code
CWE-269 Improper Privilege Management

References

Sources

CVE List CVE-2026-67543
NVD CVE-2026-67543
Maintainer advisory GHSA-hcv7-mg77-pg73

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.

The maintainers of heymrun/heym published their own advisory on GitHub. Reviewed sources take precedence over it.