Vulnerability · Published May 12, 2026 · Assigned by VulnCheck

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

High 8.8

In plain English

A high-severity security flaw in heym from heymrun. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.3% (higher than 22% of all known vulnerabilities).

Severity (CVSS 3.1)8.8High

Exploit odds (30 days)0.3%top 78.5% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official 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.

Affected products (as reported)

Vendor	Product	Versions
heymrun	heym	0 – before 0.0.21

Weakness: CWE-693 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

References

https://github.com/heymrun/heym/releases/tag/v0.0.21 release-notes
https://github.com/heymrun/heym/pull/94 issue-tracking
https://github.com/heymrun/heym/commit/32b7e809d987d9b018ec8daa2cdaf48f627f26f1 patch
https://www.vulncheck.com/advisories/heym-sandbox-escape-via-python-introspection third-party-advisory