How severe is CVE-2019-18935?

CVE-2019-18935 has a CVSS score of 9.8/10, rated CRITICAL. Immediate patching is strongly recommended.

Which products are affected by CVE-2019-18935?

CVE-2019-18935 affects the following products: telerik ui for asp.net ajax.

How do I patch CVE-2019-18935?

No patch has shipped for CVE-2019-18935 yet — track the telerik ui for asp.net ajax advisory for a fixed release and apply the workarounds below in the meantime.

How do I detect CVE-2019-18935 across my infrastructure?

Inventory every telerik ui for asp.net ajax deployment and check each version against the affected-products list above.

How do I mitigate CVE-2019-18935 if there is no patch (or I can't update yet)?

Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Is CVE-2019-18935 actively exploited in the wild?

Yes. There are 22 known exploit references for CVE-2019-18935, including 1 documented proof-of-concept exploit on Exploit-DB and 13 in-the-wild exploitations observed on GitHub and other sources. Treat this as actively exploitable and prioritize patching immediately. All exploit code should only be run in an isolated sandbox environment for research or authorized testing — never against production systems without explicit written authorization.

What is the EPSS score for CVE-2019-18935?

CVE-2019-18935 has an EPSS (Exploit Prediction Scoring System) score of 99.7%, placing it in the 100th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. A score above 50% indicates significantly elevated exploitation risk — immediate patching is strongly recommended.

Is CVE-2019-18935 in the CISA Known Exploited Vulnerabilities catalog?

Yes. CVE-2019-18935 (Progress Telerik UI for ASP.NET AJAX Deserialization of Untrusted Data Vulnerability) was added to CISA's Known Exploited Vulnerabilities (KEV) catalog on 2021-11-03. CISA required all US federal civilian agencies to remediate this vulnerability by 2022-05-03. The required action was: Apply updates per vendor instructions. This CVE has been used in known ransomware campaigns. Being listed in the KEV catalog is the strongest possible confirmation of active exploitation — treat this as a critical priority.

What type of vulnerability is CVE-2019-18935?

CVE-2019-18935 is classified as Deserialization of Untrusted Data (CWE-502). This weakness type describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

Which products and versions are affected by CVE-2019-18935?

CVE-2019-18935 affects telerik ui for asp.net ajax. Check the affected-products list on this page against your deployed version to confirm exposure.

Is there exploit tooling available for CVE-2019-18935?

2 Metasploit modules reference CVE-2019-18935, which lowers the barrier to weaponization. Public exploit tooling significantly increases real-world risk — prioritize patching and ensure detection coverage. Exploit tooling should only ever be used in isolated, authorized testing environments.

When was CVE-2019-18935 published, and has it been updated?

CVE-2019-18935 was published on December 11, 2019 and was last updated on June 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

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CISA KEV · ACTIVELY EXPLOITED

CRITICAL severity

CVE-2019-18935 — Ui For Asp.Net Ajax

CRITICAL

CVE-2019-18935 is a critical-severity (CVSS 9.8) Deserialization of Untrusted Data vulnerability in telerik ui for asp.net ajax. It is in CISA's Known Exploited Vulnerabilities catalog (added 2021-11-03) and has been used in ransomware campaigns — treat it as actively exploited and patch now. No vendor fix is recorded yet; mitigation options are listed below.

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…

Published

Dec 11, 2019

Updated

Jun 17, 2026

Affected

1 product

Patched

See advisory

Exploits

22 known

Exploitation data as of Oct 24, 2026 · OSV.dev, NVD, CISA KEV, FIRST.org (EPSS)

Exploitation Status

Actively exploited in the wild

Confirmed by CISA's Known Exploited Vulnerabilities catalog on 2021-11-03 — including use in ransomware campaigns. Federal agencies were required to remediate by 2022-05-03.
CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.

Exploitation and automatability from CISA (KEV catalog and SSVC triage) for CVE-2019-18935.

EPSS Exploitation Probability

via FIRST.org ↗

99.7%probability of exploitation in next 30 days

Very High Risk0.00%

Lower risk than most CVEs100th percentile — riskier than 100% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

How urgent is this, really

CVE-2019-18935 by exploitation likelihood (EPSS) against impact (CVSS). In the shaded patch-first corner (EPSS 50%+, CVSS 7.0+).

Where this sits among everything scored

Of 394,803 CVEs with a current EPSS score, this one falls in the ≥ 90% band (highlighted). Counts from FIRST.org, log-scaled.

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.)

Affected Products

1 product · 1 configurations

Application

ui for asp.net ajaxtelerik

≥ 2011.1.315 && ≤ 2020.1.114

range

Exploits & PoCs

Research use only. For defensive security, authorized penetration testing, and academic research only. Never execute exploit code against systems without explicit written authorization.

EDB-47793webappsaspx

Telerik UI - Remote Code Execution via Insecure Deserialization

by Bishop Fox · Dec 18, 2019

Exploit-DB Source

Detection & mitigation playbook

Vendor / appliance

Detect
Inventory every telerik ui for asp.net ajax deployment and check each version against the affected-products list above.
Remediation status
No patch has shipped for CVE-2019-18935 yet — track the telerik ui for asp.net ajax advisory for a fixed release and apply the workarounds below in the meantime.
Mitigate without a patch
Do not deserialise data from untrusted sources: where the format allows it, restrict deserialisation to an explicit allowlist of expected types, and prefer a data-only format (JSON, Protobuf) over one that can reconstruct arbitrary objects until you can upgrade. Alongside that, restrict the management interface to trusted networks and apply the vendor's recommended configuration mitigations.

Frequently Asked Questions

O3 Security · Runtime Protection

Is CVE-2019-18935 being exploited in your environment?

Detect and block the exploit chain at execution, on systems you cannot patch yet.

Protect my workloads How runtime protection works