Exploited CVEs / Progress / CVE-2019-18935
CVE-2019-18935
Progress Telerik UI for ASP.NET AJAX Deserialization of Untrusted Data Vulnerability. Exploitation in the wild is confirmed by CISA, not predicted, and the vulnerability is known to be used in ransomware campaigns. Federal agencies were required to remediate by 2022-05-03 (that deadline has passed); treat that date as the outer bound for your own environment. The fix is in the vendor advisory: Progress Security Advisories, linked below.
Actively exploited Progress Telerik UI for ASP.NET AJAX vulnerability, Critical severity, CVSS 9.8. Added to the CISA KEV catalog 2021-11-03.
Risk summary
Updated July 27, 2026. Data refreshed on every build from MSRC, CISA KEV, and FIRST EPSS.
Senserva AI Opinion for CVE-2019-18935
Progress Telerik UI for ASP.NET AJAX deserializes untrusted data in its RadAsyncUpload handler, executing attacker code inside the w3wp.exe IIS worker process, and EPSS holds at the 100% maximum. The component is embedded invisibly in thousands of custom .NET web applications, so owners often do not know they run it; ransomware groups and state actors have both exploited it, including against a US federal agency per public advisories. Critical Severity and still being found in production apps today.
Do this: Search your IIS servers for Telerik.Web.UI.dll, record each version, and upgrade or remove every build older than the 2020 fixed releases.
AI-generated from public data, 2026-07-07. Verify against the vendor advisory before acting.
Senserva AI Opinion and rich prompt for CVE-2019-18935
Copy this prompt into Claude, ChatGPT, or Copilot. The facts are included, sourced from this page.
Full tracking and change history for CVE-2019-18935
Published and last-revised dates are authoritative, from Microsoft MSRC (or the CISA KEV date-added). Senserva additionally records day-to-day changes from 2026-07-07, refreshed several times a day; the change count reflects that forward-only tracking.
CISA required action
Federal (BOD 22-01) remediation due date: 2022-05-03 (past due).
Apply updates per vendor instructions.
Official fix for CVE-2019-18935
The authoritative fix and affected-version list are published by the vendor. Find the Telerik UI for ASP.NET AJAX advisory on Progress Security Advisories.
Common questions about CVE-2019-18935
Is CVE-2019-18935 actively exploited?
Yes. CVE-2019-18935 was added to the CISA Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03, which means exploitation in the wild has been confirmed, not predicted. Its EPSS 30-day exploitation probability is 100%. CISA also reports it is known to be used in ransomware campaigns.
What is the CISA deadline and required action for CVE-2019-18935?
CISA set the federal (BOD 22-01) remediation due date at 2022-05-03, which has passed; treat any unremediated system as overdue. The verbatim required action: Apply updates per vendor instructions.
What fixes CVE-2019-18935?
The authoritative fix is in the vendor advisory: see Progress Security Advisories for the patched Telerik UI for ASP.NET AJAX versions and any workarounds. KEV listing makes this a fix-first item: patch it ahead of higher-CVSS issues nobody is exploiting.
Can I ask my own AI about CVE-2019-18935?
Yes. This page includes a free, ready-to-paste AI prompt containing CVE-2019-18935's key facts: severity, CVSS, EPSS, the KEV date, the CISA due date, and the required action. Copy it into Claude, ChatGPT, or Copilot; the data is refreshed twice a day (5 AM and 3 PM US Central).
More exploited Progress CVEs
The newest Progress entries on the CISA KEV catalog:
All Progress exploited CVEs on one page: Progress vulnerabilities actively exploited.
Authoritative references
Every actively exploited CVE, searchable with due dates and CSV export: the exploited-CVE tracker. The newest additions: exploited this week.
