CVE-2026-100643 — SiYuan versions before v3.8.4 fail to properly escape four stored Attribute View values…¶

Key facts

CVE-2026-100643 is a High (8.0) vulnerability: SiYuan versions before v3.8.4 fail to properly escape four stored Attribute View values…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-100643
Severity	High (8.0)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-100643/

Details¶

English | 한국어

Description¶

SiYuan versions before v3.8.4 fail to properly escape four stored Attribute View values in textarea elements, allowing authenticated attackers to inject JavaScript by modifying field descriptions, template sources, select option descriptions, or footer calculation templates. Attackers can execute stored JavaScript when other users open affected database menus, and in the Electron desktop app with nodeIntegration enabled, this leads to command execution with SiYuan process privileges.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-100643
Type	XSS
CVSS Score	8.0

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-100643/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-2026-100643

# 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/siyuan-note/siyuan/security/advisories/GHSA-h3p6-c22r-fx2j
https://www.vulncheck.com/advisories/siyuan-before-3.8.4-stored-xss-via-attribute-view-textarea

Generated by PoC Generator on 2026-09-27T04:19:09.782914233

Frequently asked questions¶

What is CVE-2026-100643?¶

CVE-2026-100643 is a High (8.0) vulnerability: SiYuan versions before v3.8.4 fail to properly escape four stored Attribute View values…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-100643?¶

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-2026-100643?¶

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.