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.
The CVSS severity warrants an early asset and exposure review.
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.
Confirm exposure before applying a vendor-supported change.
Confirm that Progress Software Telerik UI for ASP.NET AJAX and an affected version are present.
Combine exploitation signals with asset exposure and business criticality.
Follow the vendor advisory or supported update path and preserve rollback options.
Recheck the version, service health, access paths, and relevant logs.
