---
title: "CVE-2026-33057: Mesop Affected by Unauthenticated Remote Code Execution via Test Suite Route /exec-py"
url: https://erroneo.us/security/cve/CVE-2026-33057/
description: "CVE-2026-33057 (mesop (PyPI)): Mesop is a Python-based UI framework that allows users to build web applications. In versions 1.2.2 and below, an explicit…"
type: vulnerability-record
section: "Security Digest"
date_published: 2026-03-20
date_modified: 2026-03-25
publisher: erroneo.us
author: erroneo.us Security Desk
cve: "CVE-2026-33057"
kev: false
cvss: 9.8
epss: 0.04111
license: All rights reserved. Quote with attribution and a link.
---

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

**Signal:** Critical and remotely reachable. No known exploitation yet, but it is network-reachable without credentials. (Computed from CISA KEV, EPSS and CVSS; not an editorial verdict.)

## Should you act?

- Not in CISA KEV , but CISA’s SSVC assessment records a public proof-of-concept, so attack code exists.
- EPSS 4.1% , percentile 91: FIRST’s model estimates a 4.1% chance of exploitation activity in the next 30 days, higher than 91% of all scored CVEs (elevated). EPSS is a probability, not a verdict.
- Remotely reachable with no login and no user interaction. If the vulnerable service is exposed to the internet, prioritize it.
- Only applies if your dependency tree includes mesop (PyPI) <= 1.2.2, fixed in 1.2.3 . Check your lockfile, including transitive dependencies.

## What it is

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/wsgiapp.py. The /exec-py route accepts base64 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 executemodule(modulepath...). This issue has been fixed in version 1.2.3.

## Affected packages

- PyPI `mesop` <= 1.2.2 → fixed: 1.2.3

## Affected products (CVE record)

- mesop-dev mesop: < 1.2.3

## Severity

- GitHub_M CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`
- GitHub CVSS 3.1: 9.8 `CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H`

## Exploitation

- CISA KEV: not listed (no confirmed in-the-wild exploitation known to CISA).
- CISA SSVC assessment: exploitation poc , automatable yes , technical impact total .
- FIRST EPSS (model of 2026-10-21): 4.11% probability of exploitation activity in the next 30 days; percentile 91.

## Sources

- [GitHub Advisory GHSA-gjgx-rvqr-6w6v](https://github.com/advisories/GHSA-gjgx-rvqr-6w6v)
- [CVE.org record CVE-2026-33057](https://www.cve.org/CVERecord?id=CVE-2026-33057)
- [NVD entry CVE-2026-33057](https://nvd.nist.gov/vuln/detail/CVE-2026-33057)
- [github.com](https://github.com/mesop-dev/mesop/security/advisories/GHSA-gjgx-rvqr-6w6v)
- [github.com](https://github.com/mesop-dev/mesop/commit/825f55970c20686de3f28e2c66df4d74e9d4db47)

---
Source page: https://erroneo.us/security/cve/CVE-2026-33057/ · Security Digest: https://erroneo.us/security/ · More: https://erroneo.us/llms.txt