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8.8
HIGH CVSS 3.1
CVE-2026-55376
heym Python Tool Sandbox Escape
Overview
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.

Details
INFO

Published Date :

Oct. 13, 2026, 4:17 p.m.

Last Modified :

Oct. 13, 2026, 4:17 p.m.

Remotely Exploit :

Yes !

Source :

[email protected]
Impact
Affected Products

The following products are affected by CVE-2026-55376 vulnerability. Even if cvefeed.io is aware of the exact versions of the products that are affected, the information is not represented in the table below.

No affected product recoded yet

: Total Affected Vendor : 0 | Products : 0
Scoring
CVSS Scores
The Common Vulnerability Scoring System is a standardized framework for assessing the severity of vulnerabilities in software and systems. We collect and displays CVSS scores from various sources for each CVE.
Score Version Severity Vector Exploitability Score Impact Score Source
CVSS 3.1 HIGH MITRE-CVE
CVSS 3.1 HIGH [email protected]
Solution
Update Heym to version 0.0.40 or later to fix the Python tool execution vulnerability.
  • Update Heym to version 0.0.40.
  • Review Python tool execution policies.
  • Restrict agent creation privileges.
  • Monitor backend application user activity.
References
References to Advisories, Solutions, and Tools

Here, you will find a curated list of external links that provide in-depth information, practical solutions, and valuable tools related to CVE-2026-55376.

URL Resource
https://github.com/heymrun/heym/commit/b36d795c6ea841b8f1b511a0952e274487ee4ef3
https://github.com/heymrun/heym/releases/tag/v0.0.40
https://github.com/heymrun/heym/security/advisories/GHSA-wcgw-9hfw-f6f2
CWE - Common Weakness Enumeration

While CVE identifies specific instances of vulnerabilities, CWE categorizes the common flaws or weaknesses that can lead to vulnerabilities. CVE-2026-55376 is associated with the following CWEs:

Common Attack Pattern Enumeration and Classification (CAPEC)

Common Attack Pattern Enumeration and Classification (CAPEC) stores attack patterns, which are descriptions of the common attributes and approaches employed by adversaries to exploit the CVE-2026-55376 weaknesses.

CAPEC-6: Argument Injection Argument Injection CAPEC-15: Command Delimiters Command Delimiters CAPEC-43: Exploiting Multiple Input Interpretation Layers Exploiting Multiple Input Interpretation Layers CAPEC-88: OS Command Injection OS Command Injection CAPEC-108: Command Line Execution through SQL Injection Command Line Execution through SQL Injection CAPEC-35: Leverage Executable Code in Non-Executable Files Leverage Executable Code in Non-Executable Files CAPEC-77: Manipulating User-Controlled Variables Manipulating User-Controlled Variables CAPEC-242: Code Injection Code Injection CAPEC-1: Accessing Functionality Not Properly Constrained by ACLs Accessing Functionality Not Properly Constrained by ACLs CAPEC-17: Using Malicious Files Using Malicious Files CAPEC-20: Encryption Brute Forcing Encryption Brute Forcing CAPEC-22: Exploiting Trust in Client Exploiting Trust in Client CAPEC-36: Using Unpublished Interfaces or Functionality Using Unpublished Interfaces or Functionality CAPEC-51: Poison Web Service Registry Poison Web Service Registry CAPEC-57: Utilizing REST's Trust in the System Resource to Obtain Sensitive Data Utilizing REST's Trust in the System Resource to Obtain Sensitive Data CAPEC-59: Session Credential Falsification through Prediction Session Credential Falsification through Prediction CAPEC-65: Sniff Application Code Sniff Application Code CAPEC-74: Manipulating State Manipulating State CAPEC-87: Forceful Browsing Forceful Browsing CAPEC-107: Cross Site Tracing Cross Site Tracing CAPEC-127: Directory Indexing Directory Indexing CAPEC-237: Escaping a Sandbox by Calling Code in Another Language Escaping a Sandbox by Calling Code in Another Language CAPEC-477: Signature Spoofing by Mixing Signed and Unsigned Content Signature Spoofing by Mixing Signed and Unsigned Content CAPEC-480: Escaping Virtualization Escaping Virtualization CAPEC-668: Key Negotiation of Bluetooth Attack (KNOB) Key Negotiation of Bluetooth Attack (KNOB)

We scan GitHub repositories to detect new proof-of-concept exploits. Following list is a collection of public exploits and proof-of-concepts, which have been published on GitHub (sorted by the most recently updated).

Results are limited to the first 15 repositories due to potential performance issues.

The following list is the news that have been mention CVE-2026-55376 vulnerability anywhere in the article.

Results are limited to the first 20 news articles due to potential performance issues.

The following table lists the changes that have been made to the CVE-2026-55376 vulnerability over time.

Vulnerability history details can be useful for understanding the evolution of a vulnerability, and for identifying the most recent changes that may impact the vulnerability's severity, exploitability, or other characteristics.

  • New CVE Received by [email protected]

    Oct. 13, 2026

    Action Type Old Value New Value
    Added 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.
    Added CVSS V3.1 AV:N/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
    Added CWE CWE-94
    Added CWE CWE-78
    Added CWE CWE-693
    Added Affected New affected value received. <a href="https://github.com/CVEProject/cvelistV5/blob/main/cves/2026/55xxx/CVE-2026-55376.json">CVE-2026-55376</a>
    Added Reference https://github.com/heymrun/heym/commit/b36d795c6ea841b8f1b511a0952e274487ee4ef3
    Added Reference https://github.com/heymrun/heym/releases/tag/v0.0.40
    Added Reference https://github.com/heymrun/heym/security/advisories/GHSA-wcgw-9hfw-f6f2
EPSS is a daily estimate of the probability of exploitation activity being observed over the next 30 days. Following chart shows the EPSS score history of the vulnerability.
CVSS
Vulnerability Scoring Details
Base CVSS Score: 8.8
Attack Vector
Attack Complexity
Privileges Required
User Interaction
Scope
Confidentiality Impact
Integrity Impact
Availability Impact