CVE-2026-13184: RadAsyncUpload Default HMAC Key Fallback Vulnerability in Telerik UI for ASP.NET AJAX

Severity: high (CVSS 7.5 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.3% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-07-22 · updated 2026-10-24
Weakness: CWE-321

Description

In Progress® Telerik® UI for AJAX prior to v2026.2.708, when Telerik.Upload.ConfigurationHashKey is absent and machineKey is not explicitly configured, upload metadata integrity protection may fall back to a predictable default key, enabling attackers to forge protected upload metadata and unlock further exploit chains.

Affected products

Progress Software Telerik UI for ASP.NET AJAX: from 2010.1309 before 2026.2.708 — fixed in 2026.2.708

How to fix

Upgrade to a fixed version: Progress Software Telerik UI for ASP.NET AJAX 2026.2.708. Check the vendor advisory for mitigations.

References

https://www.telerik.com/products/aspnet-ajax/documentation/knowledge-base/kb-security-rau-unauth-deserialization-chain-cve-2026-13184

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