CVE-2026-73673 — Netis NC63 router firmware V3.0.0.3327 contains an unauthenticated firmware update…¶
Key facts
CVE-2026-73673 is a High (8.8) vulnerability: Netis NC63 router firmware V3.0.0.3327 contains an unauthenticated firmware update…. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-73673 |
| Severity | High (8.8) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-73673/ |
Details¶
English | 한국어
Description¶
Netis NC63 router firmware V3.0.0.3327 contains an unauthenticated firmware update vulnerability that allows unauthenticated attackers to submit unsigned firmware images by exploiting a missing authentication enforcement flaw in the Boa web server and netis.cgi CGI dispatcher. Attackers can send a multipart POST request to /cgi-bin/upload_fw.cgi without a valid session cookie, bypassing authentication because Boa grants access to any path containing '.cgi' regardless of cookie validation, and netis.cgi reads but does not enforce the authentication state before invoking the firmware update handler, which accepts images validated only by a forgeable additive checksum and static product strings rather than a cryptographic signature, potentially enabling persistent router compromise.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-73673 |
| Type | RCE |
| CVSS Score | 8.8 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-73673/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-2026-73673
# 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/ozcanpng/CVE-2026-73673
- https://ozcanpng.dev/blog/cve-2026-73673-netis-nc63-unauthenticated-firmware-update/
- https://www.netis-systems.com/detail/proid/307/NC63.html
- https://www.vulncheck.com/advisories/netis-nc63-unauthenticated-firmware-update-with-missing-cryptographic-firmware-authentication
Generated by PoC Generator on 2026-08-15T00:09:12.632801463
Frequently asked questions¶
What is CVE-2026-73673?¶
CVE-2026-73673 is a High (8.8) vulnerability: Netis NC63 router firmware V3.0.0.3327 contains an unauthenticated firmware update…. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-73673?¶
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-2026-73673?¶
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.