CVE-2026-66421 — OpenClaw Dashboard contains a stored cross-site scripting vulnerability that allows…¶

Key facts

CVE-2026-66421 is a Critical (9.3) vulnerability: OpenClaw Dashboard contains a stored cross-site scripting vulnerability that allows…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-66421
Severity	Critical (9.3)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-66421/

Details¶

English | 한국어

Description¶

OpenClaw Dashboard contains a stored cross-site scripting vulnerability that allows unauthenticated remote attackers to execute arbitrary JavaScript in the administrator's browser session by injecting HTML markup into agent transcript messages processed through the sessions API. Attackers can craft a message containing inline event handler payloads such as an img tag with an onerror attribute within the 60-character rendering budget, which is stored in the session transcript and interpolated unsanitized into innerHTML on the default landing page, allowing theft of session tokens and unauthorized calls to authenticated administrative endpoints including agent instruction file modification.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-66421
Type	XSS
CVSS Score	9.3

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-66421/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-2026-66421

# 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/theopaid/Stored-Cross-Site-Scripting-Via-Agent-Messages-Leading-To-Session-Token-Theft-openclaw-dashboard-
https://github.com/tugcantopaloglu/openclaw-dashboard
https://www.vulncheck.com/advisories/openclaw-dashboard-stored-xss-via-lastmessage-session-field
https://github.com/theopaid/Stored-Cross-Site-Scripting-Via-Agent-Messages-Leading-To-Session-Token-Theft-openclaw-dashboard-

Generated by PoC Generator on 2026-08-01T21:55:29.237130731

Frequently asked questions¶

What is CVE-2026-66421?¶

CVE-2026-66421 is a Critical (9.3) vulnerability: OpenClaw Dashboard contains a stored cross-site scripting vulnerability that allows…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-66421?¶

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-2026-66421?¶

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.