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MesopApplication · Mesop Dev

CVE-2026-33057

CRITICAL · 9.8 CVSS v3.1 Published 2026-03-20
Fix available
A fix is available. Upgrade to 1.2.3 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click Patch available

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
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.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Mesop versions 1.2.2 and below contain an unrestricted remote code execution vulnerability in the ai/sandbox/wsgi_app.py testing module. The /exec-py endpoint accepts base64-encoded Python code via the code parameter in POST requests and unconditionally evaluates it using execute_module() without any authentication, allowing any attacker with network access to execute arbitrary commands on the host machine.

MitigationImmediately upgrade Mesop to version 1.2.3 or later. Additionally, ensure the ai/sandbox debugging module is not exposed in production environments and audit systems for signs of compromise, as this vulnerability grants full command execution capabilities.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
MesopApplication
Affected:< 1.2.3

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Check installed Mesop version
    Run `pip show mesop` or `python -c "import mesop; print(mesop.__version__)"` to determine the installed version
    Affected if Version is 1.2.2 or lower (less than 1.2.3)
  2. Locate the ai/sandbox module
    Search for the file ai/sandbox/wsgi_app.py in the Mesop installation directory using `python -c "import mesop; print(mesop.__file__)"` to find the base path, then check for the sandbox module
    Affected if The file ai/sandbox/wsgi_app.py exists in the Mesop installation
  3. Verify if the /exec-py endpoint is registered
    Inspect the wsgi_app.py source code to confirm the /exec-py route is defined and check if the execute_module() function is called without authentication checks
    Affected if The /exec-py endpoint exists and lacks authentication logic
  4. Test endpoint accessibility (if running)
    If Mesop is running, send a POST request to /exec-py with a base64-encoded code parameter (e.g., code=ZXhlYygncHJpbnQoJzEyMycp'))
    Affected if The endpoint responds and accepts code execution without requiring credentials

You are affected if running Mesop version below 1.2.3 with the ai/sandbox/wsgi_app.py module present and the /exec-py endpoint accessible.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 1.2.3 or later
Fixed in 1.2.3
Vendor patch github.com →
Interim mitigation

Immediately upgrade Mesop to version 1.2.3 or later. Additionally, ensure the ai/sandbox debugging module is not exposed in production environments and audit systems for signs of compromise, as this vulnerability grants full command execution capabilities.

Recommended fix High confidence

Mesop >= 1.2.3

  1. Upgrade Mesop to version 1.2.3 or later by running: pip install mesop>=1.2.3
  2. Verify the upgrade was successful by running: pip show mesop and checking the version number
  3. Ensure any services running the vulnerable Mesop version are restarted to load the fixed version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mesop Scoped from the published advisory
  • Consultation4.0 h
  • Implementation2.0 h
  • Testing4.0 h
  • Review / QA2.0 h
12.0 hours of engineering $2,120
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2026-33057 in production — separate from our analysis above.

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What this is

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What belongs here
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  • Version or environment caveats, and links to real fixes
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