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CVE-2019-18935 — Progress Telerik UI for ASP.NET AJAX through 2019.3.1023 contains a .NET deserialization…

Key facts

CVE-2019-18935 is a Critical (9.8) vulnerability: Progress Telerik UI for ASP.NET AJAX through 2019.3.1023 contains a .NET deserialization…. 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, and is linked to known ransomware campaigns.

Actively exploited — on the CISA KEV catalog

CVE-2019-18935 is listed on the CISA Known Exploited Vulnerabilities (KEV) catalog (added 2021-11-03), confirming exploitation in the wild. It is linked to known ransomware campaigns. Federal remediation deadline: 2022-05-03. Prioritise patching and deploy the detection and prevention rules below.
CVE CVE-2019-18935
Severity Critical (9.8)
CISA KEV Actively exploited (added 2021-11-03) · ransomware
Detection / prevention —
PoC poc.py
Source 2019/CVE-2019-18935/

Details

English | 한국어

Description

Progress Telerik UI for ASP.NET AJAX through 2019.3.1023 contains a .NET deserialization vulnerability in the RadAsyncUpload function. This is exploitable when the encryption keys are known due to the presence of CVE-2017-11317 or CVE-2017-11357, or other means. Exploitation can result in remote code execution. (As of 2020.1.114, a default setting prevents the exploit. In 2019.3.1023, but not earlier versions, a non-default setting can prevent exploitation.)

Vulnerability Details

Property Value
CVE ID CVE-2019-18935
Type RCE
CVSS Score 9.8

Proof of Concept

Download

# Download PoC script
curl -O https://raw.githubusercontent.com/fankh/vulnerability-poc/main/2019/CVE-2019-18935/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-2019-18935

# 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

  • http://packetstormsecurity.com/files/155720/Telerik-UI-Remote-Code-Execution.html
  • http://packetstormsecurity.com/files/159653/Telerik-UI-ASP.NET-AJAX-RadAsyncUpload-Deserialization.html
  • https://codewhitesec.blogspot.com/2019/02/telerik-revisited.html
  • https://github.com/bao7uo/RAU_crypto
  • https://github.com/noperator/CVE-2019-18935
  • https://know.bishopfox.com/research/cve-2019-18935-remote-code-execution-in-telerik-ui
  • https://www.bleepingcomputer.com/news/security/us-federal-agency-hacked-using-old-telerik-bug-to-steal-data/
  • https://www.telerik.com/support/kb/aspnet-ajax/details/allows-javascriptserializer-deserialization
  • https://www.telerik.com/support/whats-new/aspnet-ajax/release-history/ui-for-asp-net-ajax-r1-2020-%28version-2020-1-114%29
  • https://www.telerik.com/support/whats-new/release-history
  • http://packetstormsecurity.com/files/155720/Telerik-UI-Remote-Code-Execution.html
  • http://packetstormsecurity.com/files/159653/Telerik-UI-ASP.NET-AJAX-RadAsyncUpload-Deserialization.html
  • https://codewhitesec.blogspot.com/2019/02/telerik-revisited.html
  • https://github.com/bao7uo/RAU_crypto
  • https://github.com/noperator/CVE-2019-18935
  • https://know.bishopfox.com/research/cve-2019-18935-remote-code-execution-in-telerik-ui
  • https://www.bleepingcomputer.com/news/security/us-federal-agency-hacked-using-old-telerik-bug-to-steal-data/
  • https://www.telerik.com/support/kb/aspnet-ajax/details/allows-javascriptserializer-deserialization
  • https://www.telerik.com/support/whats-new/aspnet-ajax/release-history/ui-for-asp-net-ajax-r1-2020-%28version-2020-1-114%29
  • https://www.telerik.com/support/whats-new/release-history
  • https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2019-18935

Generated by PoC Generator on 2026-07-02T00:54:05.552156228

Frequently asked questions

What is CVE-2019-18935?

CVE-2019-18935 is a Critical (9.8) vulnerability: Progress Telerik UI for ASP.NET AJAX through 2019.3.1023 contains a .NET deserialization…. 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, and is linked to known ransomware campaigns.

How do I detect CVE-2019-18935?

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-2019-18935?

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-2019-18935 actively exploited?

Yes. CVE-2019-18935 is on the CISA Known Exploited Vulnerabilities (KEV) catalog, added 2021-11-03, which means it has been exploited in the wild. CISA also links it to known ransomware campaigns. CISA set a federal remediation deadline of 2022-05-03. Prioritise patching and deploy the detection and prevention rules above.

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