CVE-2026-57155 — OPNsense is a FreeBSD based firewall and routing platform.¶

Key facts

CVE-2026-57155 is a Critical (9.9) vulnerability: OPNsense is a FreeBSD based firewall and routing platform.. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-57155
Severity	Critical (9.9)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-57155/

Details¶

English | 한국어

Description¶

OPNsense is a FreeBSD based firewall and routing platform. Prior to version 26.1.11, the Firewall Alias GeoIP importer's process_zip() and process_gzip() paths in src/opnsense/scripts/filter/lib/alias/geoip.py use an unvalidated CSV country_code value to construct output filenames below /usr/local/share/GeoIP/alias. A user with Firewall Alias Edit privilege can configure an attacker-controlled GeoIP source URL and supply an archive whose country code traverses into another existing directory, causing attacker-controlled content to be written as root with an -IPv4 or -IPv6 suffix. A crafted newsyslog fragment and oversized log file can use the default hourly root cron job to execute commands as root, resulting in complete firewall compromise. This issue is fixed in version 26.1.11.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-57155
Type	RCE
CVSS Score	9.9

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-57155/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-2026-57155

# 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/opnsense/core/commit/c46aced9c47d956167e294911113bc334fea5f48
https://github.com/opnsense/core/commit/e7fbfaa7f5e070da667e3f243da11fd3d4b731fa
https://github.com/opnsense/core/security/advisories/GHSA-wjqq-rfmm-v5h3
https://hackerask.com/posts/opnsense
https://github.com/opnsense/core/security/advisories/GHSA-wjqq-rfmm-v5h3

Generated by PoC Generator on 2026-10-16T03:14:48.306304016

Frequently asked questions¶

What is CVE-2026-57155?¶

CVE-2026-57155 is a Critical (9.9) vulnerability: OPNsense is a FreeBSD based firewall and routing platform.. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-57155?¶

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-2026-57155?¶

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.