CVE-2026-81522 — A weakness in the MongoDB C++ Driver's handling of caller-supplied namespace identifiers…¶

Key facts

CVE-2026-81522 is a High (8.1) vulnerability: A weakness in the MongoDB C++ Driver's handling of caller-supplied namespace identifiers…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-81522
Severity	High (8.1)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-81522/

Details¶

English | 한국어

Description¶

A weakness in the MongoDB C++ Driver's handling of caller-supplied namespace identifiers allows special characters embedded in those identifiers. An application that builds a namespace identifier from untrusted input without validating it may therefore have its operation directed at a different target than intended. This can result in limited unauthorized read and write access to data belonging to another logical tenant of the affected application.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-81522
CVSS Score	8.1

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-81522/poc.py

Usage¶

# Run PoC against target
python3 poc.py --target <TARGET_URL>

# With authentication
python3 poc.py --target <TARGET_URL> --username <USER> --password <PASS>

⚠️ Warning: This PoC is for authorized security testing only. It uses detection-only techniques and does not exploit or damage target systems.

Test Lab¶

This repository includes a Docker-based test environment with both vulnerable and patched applications.

Quick Start¶

# Clone and navigate to CVE directory
cd CVE-2026-81522

# Start both applications
docker-compose up -d

# Run tests
./run-tests.sh    # Linux/Mac
./run-tests.ps1   # Windows PowerShell

Application Endpoints¶

Application	URL	Status
Vulnerable App	http://localhost:8080	Shows vulnerability
Patched App	http://localhost:8081	Demonstrates fix

Directory Structure¶

├── README.md           # English documentation
├── README_KO.md        # Korean documentation
├── poc.py              # PoC detection script
├── docker-compose.yml  # Container orchestration
├── run-tests.sh        # Linux/Mac test runner
├── run-tests.ps1       # Windows test runner
├── vulnerable-app/     # Vulnerable version
│   ├── app.py
│   ├── Dockerfile
│   └── requirements.txt
└── patched-app/        # Fixed version
    ├── app.py
    ├── Dockerfile
    └── requirements.txt

References¶

https://github.com/mongodb/mongo-cxx-driver/releases/tag/r4.5.1
https://jira.mongodb.org/browse/CXX-3552

Generated by PoC Generator on 2026-08-30T09:03:01.256828853

Frequently asked questions¶

What is CVE-2026-81522?¶

CVE-2026-81522 is a High (8.1) vulnerability: A weakness in the MongoDB C++ Driver's handling of caller-supplied namespace identifiers…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-81522?¶

Run the detection-only PoC included with this entry against your Docker test lab to confirm whether a target is affected; pair it with your own IDS logging.

How do I block or mitigate CVE-2026-81522?¶

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

For authorized security testing and research only. See the full source and NVD record.