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CVE-2021-35395 — Realtek Jungle SDK version v2.x up to v3.4.14B provides an HTTP web server exposing a…

Key facts

CVE-2021-35395 is a Critical (9.8) vulnerability: Realtek Jungle SDK version v2.x up to v3.4.14B provides an HTTP web server exposing a…. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2021-11-03), confirming active exploitation in the wild.

Actively exploited — on the CISA KEV catalog

CVE-2021-35395 is listed on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2021-11-03), confirming exploitation in the wild. Federal remediation deadline: 2021-11-17. Prioritise patching and deploy the detection and prevention rules below.
CVE CVE-2021-35395
Severity Critical (9.8)
CISA KEV Actively exploited (added 2021-11-03)
Detection / prevention —
PoC poc.py
Source 2021/CVE-2021-35395/

Details

English | 한국어

Description

Realtek Jungle SDK version v2.x up to v3.4.14B provides an HTTP web server exposing a management interface that can be used to configure the access point. Two versions of this management interface exists: one based on Go-Ahead named webs and another based on Boa named boa. Both of them are affected by these vulnerabilities. Specifically, these binaries are vulnerable to the following issues: - stack buffer overflow in formRebootCheck due to unsafe copy of submit-url parameter - stack buffer overflow in formWsc due to unsafe copy of submit-url parameter - stack buffer overflow in formWlanMultipleAP due to unsafe copy of submit-url parameter - stack buffer overflow in formWlSiteSurvey due to unsafe copy of ifname parameter - stack buffer overflow in formStaticDHCP due to unsafe copy of hostname parameter - stack buffer overflow in formWsc due to unsafe copy of 'peerPin' parameter - arbitrary command execution in formSysCmd via the sysCmd parameter - arbitrary command injection in formWsc via the 'peerPin' parameter Exploitability of identified issues will differ based on what the end vendor/manufacturer did with the Realtek SDK webserver. Some vendors use it as-is, others add their own authentication implementation, some kept all the features from the server, some remove some of them, some inserted their own set of features. However, given that Realtek SDK implementation is full of insecure calls and that developers tends to re-use those examples in their custom code, any binary based on Realtek SDK webserver will probably contains its own set of issues on top of the Realtek ones (if kept). Successful exploitation of these issues allows remote attackers to gain arbitrary code execution on the device.

Vulnerability Details

Property Value
CVE ID CVE-2021-35395
CVSS Score 9.8

Proof of Concept

Download

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2021/CVE-2021-35395/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-2021-35395

# 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://www.iot-inspector.com/blog/advisory-multiple-issues-realtek-sdk-iot-supply-chain
  • https://www.realtek.com/en/cu-1-en/cu-1-taiwan-en
  • https://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdf
  • https://www.iot-inspector.com/blog/advisory-multiple-issues-realtek-sdk-iot-supply-chain
  • https://www.realtek.com/en/cu-1-en/cu-1-taiwan-en
  • https://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdf
  • https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35395

Generated by PoC Generator on 2026-06-26T06:21:14.795166499

Frequently asked questions

What is CVE-2021-35395?

CVE-2021-35395 is a Critical (9.8) vulnerability: Realtek Jungle SDK version v2.x up to v3.4.14B provides an HTTP web server exposing a…. This entry ships a detection-only PoC and a Docker test lab. It is on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2021-11-03), confirming active exploitation in the wild.

How do I detect CVE-2021-35395?

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-2021-35395?

Upgrade to a fixed version per the vendor advisory; the NVD record lists the affected versions. Use the included PoC to verify your remediation.

Is CVE-2021-35395 actively exploited?

Yes. CVE-2021-35395 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2021-11-03, which means it has been exploited in the wild. CISA set a federal remediation deadline of 2021-11-17. Prioritise patching and deploy the detection and prevention rules above.

For authorized security testing and research only. See the full source and NVD record.