CVE-2026-66420 — MeshCentral 1.1.21 contains a cross-site WebSocket hijacking protection bypass…¶
Key facts
CVE-2026-66420 is a High (8.8) vulnerability: MeshCentral 1.1.21 contains a cross-site WebSocket hijacking protection bypass…. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-66420 |
| Severity | High (8.8) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-66420/ |
Details¶
English | 한국어
Description¶
MeshCentral 1.1.21 contains a cross-site WebSocket hijacking protection bypass vulnerability that allows unauthenticated remote attackers to hijack authenticated administrator sessions by exploiting an unconditional early return in the CheckWebServerOriginName() function within webserver.js when self-signed certificates are in use. Attackers can open cross-origin WebSocket connections to any of the twelve WebSocket endpoints, send crafted action commands to exfiltrate the server sessionKey used to sign session cookies, forge session tokens as arbitrary users, and gain full remote control of all managed devices governed by the MeshCentral instance.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-66420 |
| CVSS Score | 8.8 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-66420/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-2026-66420
# 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/Ylianst/MeshCentral
- https://github.com/Ylianst/MeshCentral/commit/f04c9f4
- https://github.com/Ylianst/MeshCentral/pull/7882
- https://www.vulncheck.com/advisories/meshcentral-cross-site-websocket-hijacking-via-origin-validation-bypass-on-self-signed-certificate-deployments
Generated by PoC Generator on 2026-08-01T22:11:58.292057479
Frequently asked questions¶
What is CVE-2026-66420?¶
CVE-2026-66420 is a High (8.8) vulnerability: MeshCentral 1.1.21 contains a cross-site WebSocket hijacking protection bypass…. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-66420?¶
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-2026-66420?¶
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.