CVE-2026-13684 — An improper encoding or escaping of output vulnerability in SCGI in Synology DiskStation…¶

Key facts

CVE-2026-13684 is a Critical (9.8) vulnerability: An improper encoding or escaping of output vulnerability in SCGI in Synology DiskStation…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-13684
Severity	Critical (9.8)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-13684/

Details¶

English | 한국어

Description¶

An improper encoding or escaping of output vulnerability in SCGI in Synology DiskStation Manager (DSM) before 7.2.1-69057-12, 7.2.2-72806-9, 7.3.2-86009-4 and 7.4-90075 allows remote attackers to read or write arbitrary files and conduct denial-of-service attacks.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-13684
CVSS Score	9.8

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-13684/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-2026-13684

# 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://www.synology.com/en-global/security/advisory/Synology_SA_26_13

Generated by PoC Generator on 2026-09-18T18:49:05.208837709

Frequently asked questions¶

What is CVE-2026-13684?¶

CVE-2026-13684 is a Critical (9.8) vulnerability: An improper encoding or escaping of output vulnerability in SCGI in Synology DiskStation…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-13684?¶

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-2026-13684?¶

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.