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CVE-2026-13187 – Provider Type Tampering Enabling Chained Exploitation – Telerik UI for ASP.NET A…

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Summary

CVE-2026-13187 is a high-severity provider type tampering vulnerability in the DialogHandler component of Progress® Telerik® UI for ASP.NET AJAX, affecting all versions from 2011.2.712 through 2026.2.519. Classified under CWE-470 (Use of Externally-Controlled Input to Select Classes or Code), the flaw allows an unauthenticated remote attacker to manipulate provider type input processed by the DialogHandler, altering dialog processing behavior and enabling chained exploitation. Progress Software has assigned a CVSS v3.1 score of 8.1 (High) and released version 2026.2.708 (2026 Q2 SP1) as the fix.

Technical details

  • Root cause: Insufficient validation in the DialogHandler component allows externally-controlled input to select or alter the provider type used during dialog processing (CWE-470 / CAPEC-586 Object Injection).
  • Trigger conditions: The vulnerability is exploitable when all of the following apply: (1) RadEditor or RadFileExplorer is deployed on the application, and (2) DialogParametersEncryptionKey is explicitly configured in web.config, or the machineKey lacks an explicit configuration.
  • Attack vector: Network-accessible; no authentication, no user interaction, and no local access required. The DialogHandler endpoint (Telerik.Web.UI.DialogHandler.aspx) is an internet-facing HTTP handler.
  • Impact: Successful exploitation allows an attacker to alter dialog processing and use the tampered type input as a primitive to enable chained follow-on exploitation, with potential full confidentiality, integrity, and availability compromise (C:H/I:H/A:H).

Affected software

  • Progress® Telerik® UI for ASP.NET AJAX, versions 2011.2.712 through 2026.2.519 (all versions prior to 2026.2.708)

Severity

  • CVSS v3.1 Base Score: 8.1 (High)
  • Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H

Mitigation and recommended actions

  • Immediate – upgrade: Update to Telerik UI for ASP.NET AJAX version 2026.2.708 (2026 Q2 SP1) or later, which contains the vendor-provided fix.
  • If immediate upgrade is not possible – workarounds:
    • Remove any explicitly configured DialogParametersEncryptionKey value from web.config to fall back to MachineKey.Unprotect for dialog parameter protection.
    • If machineKey is not already explicitly set, generate strong machine keys in IIS using HMACSHA256 validation with the "autogenerate" option unchecked.
    • Recycle application pools after applying either configuration change.
    • Restrict network access to the Telerik.Web.UI.DialogHandler.aspx endpoint where operationally feasible.

IONIX Status

The IONIX research team is tracking ongoing exploitation attempts and recommends immediate patching. Potentially affected assets are outlined in this post.

References

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