validate route in 9router takes a caller-supplied baseUrl…¶

Key facts

CVE-2026-72860 is a High (8.5) vulnerability: The POST /api/provider-nodes/validate route in 9router takes a caller-supplied baseUrl…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-72860
Severity	High (8.5)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-72860/

Details¶

English | 한국어

Description¶

The POST /api/provider-nodes/validate route in 9router takes a caller-supplied baseUrl and issues server-side HTTP requests to it, guarding the destination with assertPublicUrl from src/shared/utils/ssrfGuard.js. That guard compares hostname strings only: it resolves no DNS, does not revalidate after a redirect, and its IPv4-mapped IPv6 branch is unreachable. The branch matches ^::ffff:(\d+.\d+.\d+.\d+)$, but the WHATWG URL parser canonicalizes such literals to hextets before the guard runs, so new URL("http://[::ffff:127.0.0.1]/").hostname yields [::ffff:7f00:1] and the pattern is tested against a string it is never handed. Every IPv4-mapped address therefore passes, and http://[::ffff:7f00:1] and http://[::ffff:a9fe:a9fe] reach loopback and link-local metadata addresses; a hostname whose A record points at an internal address passes as well because no resolution occurs. In the custom-embedding branch the upstream response body is truncated to 200 bytes and returned to the caller whenever the upstream status is neither 2xx nor 401 nor 403, which discloses the beginning of internal responses, and the other validation types remain usable for blind internal port scanning through status and timing differences. The caller-supplied apiKey is forwarded to the internal destination as an Authorization Bearer header. A dashboard session is required by default, and none is required when requireLogin is disabled.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-72860
Type	SSRF
CVSS Score	8.5

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-72860/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-2026-72860

# 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/decolua/9router
https://github.com/decolua/9router/blob/master/src/app/api/provider-nodes/validate/route.js
https://github.com/decolua/9router/blob/master/src/shared/utils/ssrfGuard.js
https://github.com/decolua/9router/issues/3293
https://github.com/decolua/9router/pull/3370
https://www.vulncheck.com/advisories/9router-server-side-request-forgery-via-api-provider-nodes-validate-because-the-ipv4-mapped-ipv6-denylist-check-is-unreachable

Generated by PoC Generator on 2026-08-22T01:54:17.424546805

Frequently asked questions¶

What is CVE-2026-72860?¶

CVE-2026-72860 is a High (8.5) vulnerability: The POST /api/provider-nodes/validate route in 9router takes a caller-supplied baseUrl…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-72860?¶

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-2026-72860?¶

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.