CVE-2026-46409 — OpenYak is a local-first agent runtime for reliable tool-using models, with a desktop…¶

Key facts

CVE-2026-46409 is a Critical (9.6) vulnerability: OpenYak is a local-first agent runtime for reliable tool-using models, with a desktop…. This entry ships a detection-only PoC and a Docker test lab.


CVE	CVE-2026-46409
Severity	Critical (9.6)
Detection / prevention	—
PoC	poc.py
Source	2026/CVE-2026-46409/

Details¶

English | 한국어

Description¶

OpenYak is a local-first agent runtime for reliable tool-using models, with a desktop workspace built on top. Prior to version 1.1.3, the OpenYak desktop backend binds an HTTP API to 127.0.0.1:<random port> (commonly 19141) without server-side Origin validation, loopback authentication, or Content-Type enforcement, and with a wildcard CORS policy. Any webpage a user visits while OpenYak is running can issue cross-origin requests to this local server — the browser acts as a proxy into loopback, bypassing OS-level network isolation. Chained, this lets a malicious page execute arbitrary shell commands on the host (RCE) via the build agent with permission_presets.bash=true, shut down the service, and exfiltrate chat history and account PII — with no user interaction beyond opening the page. Version 1.1.3 patches the issue.

Vulnerability Details¶

Property	Value
CVE ID	CVE-2026-46409
Type	RCE
CVSS Score	9.6

Proof of Concept¶

Download¶

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-46409/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-2026-46409

# 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/openyak/openyak/security/advisories/GHSA-ccxp-q2w5-27jw

Generated by PoC Generator on 2026-08-08T09:20:10.487511007

Frequently asked questions¶

What is CVE-2026-46409?¶

CVE-2026-46409 is a Critical (9.6) vulnerability: OpenYak is a local-first agent runtime for reliable tool-using models, with a desktop…. This entry ships a detection-only PoC and a Docker test lab.

How do I detect CVE-2026-46409?¶

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-2026-46409?¶

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.