CVE-2026-49819 — UpSnap is a wake on lan web app.¶

Key facts

CVE-2026-49819 is a Critical (9.8) vulnerability: UpSnap is a wake on lan web app.. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-49819
Severity	Critical (9.8)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-49819/

Details¶

English | 한국어

Description¶

UpSnap is a wake on lan web app. Versions 4.4.1 through 5.3.5 are vulnerable to a missing-authentication / privilege-escalation chain in pb.HandlerInitSuperuser (backend/pb/handlers.go:249), reachable as POST /api/upsnap/init-superuser. The vulnerable code lacks any authentication, setup token, IP allow-list, or rate limit and is gated only by a totalSuperusers > 0 count check — a condition that is false on every fresh install — allowing an unauthenticated network-adjacent attacker to register the initial superuser account, receive a long-lived JWT, and pivot to root remote code execution at backend/networking/wake.go:43 (exec.CommandContext(ctx, "/bin/sh", "-c", wake_cmd)). Version 5.4.0 fixes the issue.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-49819
Type	RCE
CVSS Score	9.8

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-49819/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-2026-49819

# 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/seriousm4x/UpSnap/releases/tag/5.4.0
https://github.com/seriousm4x/UpSnap/security/advisories/GHSA-w4jr-728f-5jhq

Generated by PoC Generator on 2026-08-13T12:42:28.329191019

Frequently asked questions¶

What is CVE-2026-49819?¶

CVE-2026-49819 is a Critical (9.8) vulnerability: UpSnap is a wake on lan web app.. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-49819?¶

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-2026-49819?¶

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.