# CVE-2026-13183 — Progress Software Telerik UI for ASP.NET AJAX

> As of 2026-07-22, CVE-2026-13183 is a HIGH-severity vulnerability in Progress Software Telerik UI for ASP.NET AJAX, CVSS v3.1 7.5, EPSS 0.4% (36.8th percentile). Threadlinqs Intelligence links 1 tracked threat campaign to CVE-2026-13183, most recently “Telerik UI for ASP.NET AJAX — Padding Oracle Chained to Unauthenticated Deserialization RCE (CVE-2026-13181–13184)”.

**Last updated:** 2026-07-22

## What is CVE-2026-13183?

In Progress® Telerik® UI for AJAX prior to v2026.2.708, RadAsyncUpload upload metadata processing may leak cryptographic validity through measurable timing differences, enabling remote attackers to recover protected metadata values.

The record classifies CVE-2026-13183 under weakness class [CWE-208](https://cwe.mitre.org/data/definitions/208.html). 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. 1 affected-product entry is recorded, across 1 vendor, listed below. The identifier was first published 80 days ago.

## Severity and exploitation probability

- **CVSS v3.1 base score:** 7.5 — HIGH (`CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N`)
- **EPSS (FIRST):** 0.4% probability of exploitation in the next 30 days, higher than 36.8% of all scored CVEs
- **CISA KEV:** Not listed in the CISA Known Exploited Vulnerabilities catalog
- **Threadlinqs priority:** 5.2/10 — a Threadlinqs composite of the CVSS base score, the EPSS percentile and public exploit availability
- **Published:** 2026-07-22

## Is CVE-2026-13183 being exploited?

It currently carries a trending score of 24 in the Threadlinqs vulnerability feed.

## Affected products and versions

- [Progress Software](https://intel.threadlinqs.com/vendors/progress-software): Telerik UI for ASP.NET AJAX

## How to fix CVE-2026-13183

No vendor patch reference has been recorded for CVE-2026-13183 in the tracked sources. Follow the references below for a fix, and treat the products listed above as exposed until the vendor states otherwise.

## Threat activity tracking CVE-2026-13183

1 tracked threat in the Threadlinqs corpus references CVE-2026-13183, either in the campaign’s CVE list or as an indicator on the campaign record.

- [Telerik UI for ASP.NET AJAX — Padding Oracle Chained to Unauthenticated Deserialization RCE (CVE-2026-13181–13184)](https://intel.threadlinqs.com/threat/TL-2026-2369) — HIGH · 2026-09-07

## Sources

Enriched from CVE.org, FIRST EPSS, GitHub Security Advisories. Last verified by Threadlinqs on 2026-10-10.

**Vendor advisory and patch**

- [telerik.com — vendor advisory](https://www.telerik.com/products/aspnet-ajax/documentation/knowledge-base/kb-security-rau-timing-oracle-CVE-2026-13183)

Canonical: https://intel.threadlinqs.com/cve/CVE-2026-13183
Full detection coverage and IOCs for threats exploiting CVE-2026-13183 via the Threadlinqs MCP server (Purple tier): https://intel.threadlinqs.com/mcp