Telerik AJAX Upload Metadata Integrity Default Key Weakness

CVE-2026-13184 affects Progress Telerik UI for AJAX versions prior to v2026.2.708, where missing explicit configuration of Telerik.Upload.ConfigurationHashKey and machineKey creates a cryptographic weakness. When these security controls are absent, the upload metadata integrity protection mechanism defaults to a predictable key, allowing attackers to forge upload metadata without authorization. This vulnerability is critical for organizations deploying Telerik AJAX components in web applications, as it enables attackers to bypass upload restrictions and inject malicious files or metadata that downstream components may trust. The attack requires no authentication and can be chained with file upload exploitation to achieve code execution or data manipulation.

While MITRE ATT&CK techniques are not formally mapped to this CVE, Casky's Claude-powered analysis would detect attack patterns associated with T1190 (Exploit Public-Facing Application) and T1434 (Internal Spearphishing) by identifying anomalous upload metadata signatures that deviate from legitimate hashing patterns. Practitioners using Casky would observe findings flagging: (1) upload requests with metadata signed using weak or default cryptographic material, (2) mismatches between expected and actual ConfigurationHashKey values in application configuration, (3) machineKey validation failures across Telerik Upload components, and (4) metadata forgery attempts that succeed despite upload restrictions. These pattern detections enable security teams to identify compromised or misconfigured instances before exploitation occurs.