Vulnerability · Published Oct 13, 2026 · Assigned by GitHub_M

CVE-2026-55376heym Python Tool Sandbox Escape

High 8.8

In plain English

A high-severity OS command injection in heym from heymrun. Proof-of-concept exploit code is public. The chance it is exploited in the next 30 days is estimated at 0.5% (higher than 40% of all known vulnerabilities).

Severity (CVSS 3.1)8.8High

Exploit odds (30 days)0.5%top 60.1% of all CVEs

Exploited in the wildNo reportsCISA SSVC: poc

Attack toolingNoneno public tooling known

Official description

Heym builds and runs agentic systems and business-process automations on self-hosted infrastructure. Prior to 0.0.40, an authenticated user who can create or edit a workflow with an Agent custom Python tool can bypass the blacklist-based sandbox in backend/app/services/python_tool_executor.py because allowed standard-library modules expose operating-system, process, and filesystem capabilities through public attributes that pass _safe_import() and _validate_code_safety(). The runner then executes the supplied tool with exec(), permitting commands and file operations as the backend application user; self-registration affects reachability, but portal triggering alone does not grant code control. This issue is fixed in 0.0.40.

Affected products (as reported)

Vendor	Product	Versions
heymrun	heym	< 0.0.40

Weakness: CWE-78, CWE-94, 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/security/advisories/GHSA-wcgw-9hfw-f6f2 x_refsource_CONFIRM
https://github.com/heymrun/heym/commit/b36d795c6ea841b8f1b511a0952e274487ee4ef3 x_refsource_MISC
https://github.com/heymrun/heym/releases/tag/v0.0.40 x_refsource_MISC