CVE-2026-45227: Heymrun Heym

High severity, CVSS 8.8. EPSS: 0.4% chance of exploitation in the next 30 days.

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.

Affected products

• Heymrun Heym: before 0.0.21 (fixed in 0.0.21)

Published 2026-05-12. Last modified 2026-07-14.