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Fencer Vulns
critical 9.8

CVE-2026-33057 json

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

published 2026-03-18 7 mo ago modified 2026-07-13 3 mo ago also GHSA-gjgx-rvqr-6w6v , PYSEC-2026-412 , EUVD-2026-13618

cvss
9.8
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
6.6%
EPSS 6.6% chance of exploitation in 30 days, percentile 93%
public exploits
0
none known, plus a Nuclei check

Summary

Mesop is a Python-based UI framework that allows users to build web applications. In versions 1.2.2 and below, 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. 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...). This issue has been fixed in version 1.2.3.

Patch / fix

  • pypi mesop 1.2.3
  • mesop-dev mesop 1.2.3

CISA SSVC

Exploitation
Proof of concept is public
Automatable
yes
Technical impact
total
Assessed
7 mo ago

Exploit prediction

6.62% chance of exploitation in the next 30 days, higher than 93% of all scored CVEs (FIRST EPSS, 2026-11-08).

Exploits and checks

  • Nuclei template Mesop AI Sandbox <= 1.2.2 - Remote Code Execution nuclei detection template

CVSS scores

assigned by version score vector
CNA 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
OSV 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
GitHub 3.1 9.8 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Affected packages

ecosystem package affected fixed in
pypi mesop
<1.2.3
1.2.3

Affected products

  • mesop-dev mesop

Classification

Weakness
  • CWE-94 Improper Control of Generation of Code

References

Sources

Fencer Vulns keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.