CVE-2026-63626 — Mongoose is an embedded web server and network library.¶

Key facts

CVE-2026-63626 is a High (8.8) vulnerability: Mongoose is an embedded web server and network library.. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-63626
Severity	High (8.8)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-63626/

Details¶

English | 한국어

Description¶

Mongoose is an embedded web server and network library. Prior to 7.23, ppp_handle_ipv6cp() in src/l2_ppp.c trusts the 16-bit IPv6CP len field without checking it against the received payload size. On a PPP or PPPoE link using MG_ENABLE_TCPIP and MG_ENABLE_IPV6, an unauthenticated adjacent peer can complete the required LCP exchange and send a short Configure-Request with an oversized length, causing ppp_tx_frame() to read beyond recv_queue.buf and write beyond tx.buf. The same length misuse can also expose adjacent heap bytes in a reply or hang the event loop through find_opt(). This issue is fixed in version 7.23.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-63626
CVSS Score	8.8

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-63626/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-2026-63626

# 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/cesanta/mongoose/commit/751f14742dea934bec08a507ab1fecc3673d4903
https://github.com/cesanta/mongoose/releases/tag/7.23
https://github.com/cesanta/mongoose/security/advisories/GHSA-pc66-j6r6-49x9

Generated by PoC Generator on 2026-10-15T07:30:14.699957086

Frequently asked questions¶

What is CVE-2026-63626?¶

CVE-2026-63626 is a High (8.8) vulnerability: Mongoose is an embedded web server and network library.. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-63626?¶

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-2026-63626?¶

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.