Threat Intelligence / CVE / CVE-2019-18935

CVE-2019-18935 — Telerik Ui For Asp.net Ajax

CISA KEVRansomware
CVSS v3.1 9.8 (CRITICAL) · EPSS 93.5% (higher than 99.8% of all scored CVEs) · Priority 10/10 · Published 2019-12-11

As of 2025-11-07, CVE-2019-18935 is a CRITICAL-severity vulnerability in Telerik Ui For Asp.net Ajax, CVSS v3.1 9.8, EPSS 93.5% (99.8th percentile). It is listed in the CISA Known Exploited Vulnerabilities catalog (added 2021-11-03), with a US federal remediation deadline of 2022-05-03, and CISA links it to known ransomware campaigns. Threadlinqs Intelligence links 2 tracked threat campaigns to CVE-2019-18935, most recently “Chinese-speaking threat group UAT-10147 uses agentic AI to automate exploitation of internet-facing web servers”.

Last updated: 2025-11-07

What is CVE-2019-18935?

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.)

The record classifies CVE-2019-18935 under weakness class CWE-502. Its CVSS v3 base vector states that the flaw is reachable remotely over the network, needs no prior authentication, needs no user interaction, and has high impact on confidentiality, integrity, availability. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 2468 days ago.

Severity and exploitation probability

CVSS v3.1 base score
9.8 — CRITICAL
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
EPSS (FIRST)
93.5% probability of exploitation in the next 30 days, higher than 99.8% of all scored CVEs
CISA KEV
Listed since 2021-11-03, federal remediation deadline 2022-05-03 — used in known ransomware campaigns
Threadlinqs priority
10/10 — CISA lists it as used in ransomware, which Threadlinqs scores at the maximum
Published
2019-12-11, last modified 2025-11-07

Is CVE-2019-18935 being exploited?

CISA added CVE-2019-18935 to the Known Exploited Vulnerabilities catalog on 2021-11-03, which means the agency holds evidence of exploitation in the wild; US federal civilian agencies had to remediate it by 2022-05-03 under BOD 22-01. CISA flags the vulnerability as one used in known ransomware campaigns. It currently carries a trending score of 40 in the Threadlinqs vulnerability feed.

Affected products and versions

How to fix CVE-2019-18935

The record marks a vendor fix as available for CVE-2019-18935. Patch reference: https://docs.telerik.com/devtools/aspnet-ajax/knowledge-base/common-allows-javascriptserializer-deserialization. Vendor advisory: https://www.telerik.com/support/kb/aspnet-ajax/details/allows-javascriptserializer-deserialization. Because CVE-2019-18935 is KEV-listed, US federal civilian agencies were required to apply the vendor fix, or stop using the product, by 2022-05-03. Apply the vendor fix referenced above to every affected product listed in this record, then confirm the running version against the vendor advisory.

Threat activity tracking CVE-2019-18935

2 tracked threats in the Threadlinqs corpus reference CVE-2019-18935, either in the campaign’s CVE list or as an indicator on the campaign record.

Sources

Seeded from nvd and not yet processed by the Threadlinqs enrichment pipeline, so blank CVSS, EPSS or KEV fields above mean NOT MEASURED rather than measured-absent.

Full detection coverage & IOCs for threats exploiting CVE-2019-18935 are available via the Threadlinqs MCP server (Purple tier). View plans →

← all vulnerabilities · Markdown version · Threadlinqs Intelligence