CVE-2026-97381 — Legacy Update is a tool for activating and installing updates on legacy Windows PCs.¶
Key facts
CVE-2026-97381 is a Critical (9.9) vulnerability: Legacy Update is a tool for activating and installing updates on legacy Windows PCs.. This entry ships a detection-only PoC and a Docker test lab.
| CVE | CVE-2026-97381 |
| Severity | Critical (9.9) |
| Detection / prevention | — |
| PoC | poc.py |
| Source | 2026/CVE-2026-97381/ |
Details¶
English | 한국어
Description¶
Legacy Update is a tool for activating and installing updates on legacy Windows PCs. Legacy Update 1.12.0 through 1.13.1 contains an origin validation error in the IsPermitted method of its ActiveX control. After successfully reading the hosting document's hostname, a hostname that is not on the permitted list falls through without setting E_ACCESSDENIED, causing IsPermitted to return S_OK. An attacker who induces a user to visit a malicious webpage in Internet Explorer can invoke the control to enumerate update and system information, install updates without consent, display dialogs, or restart the computer when a reboot is pending. This issue was fixed in Legacy Update 1.13.2.
Vulnerability Details¶
| Property | Value |
|---|---|
| CVE ID | CVE-2026-97381 |
| CVSS Score | 9.9 |
Proof of Concept¶
Download¶
# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2026/CVE-2026-97381/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-2026-97381
# 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/LegacyUpdate/LegacyUpdate/commit/7d62f0bfaa770d74cd6e2cb0bac9c1907df48033
- https://github.com/LegacyUpdate/LegacyUpdate/commit/ae1c46c97f39a55a1937784d9f9beb30aa9147fd
- https://github.com/LegacyUpdate/LegacyUpdate/releases/tag/v1.13.2.0
- https://github.com/LegacyUpdate/LegacyUpdate/security/advisories/GHSA-f4g7-4gmx-jfgf
- https://legacyupdate.net/news/2026/07/21/legacy-update-1-13-2
Generated by PoC Generator on 2026-10-14T14:52:14.846429946
Frequently asked questions¶
What is CVE-2026-97381?¶
CVE-2026-97381 is a Critical (9.9) vulnerability: Legacy Update is a tool for activating and installing updates on legacy Windows PCs.. This entry ships a detection-only PoC and a Docker test lab.
How do I detect CVE-2026-97381?¶
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-2026-97381?¶
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.