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CVE-2026-13185 – Unauthenticated RCE via Cookie Deserialization – Telerik UI for ASP.NET AJAX pri…

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Summary

CVE-2026-13185 is a high-severity insecure deserialization vulnerability (CWE-502) in Progress Telerik UI for ASP.NET AJAX affecting all versions from 2013.1.220 up to and including 2026.2.519. When an application uses cookie-based state storage in the RadPersistenceManager or RadDockLayout components, attacker-controlled cookie content is deserialized without sufficient validation, enabling unauthenticated remote code execution (RCE) on the server. Progress Software has released a fix in version 2026.2.708 (Q2 SP1).

Technical details

  • Root cause: Deserialization of untrusted data (CWE-502) — the affected components deserialize cookie values directly from client-supplied HTTP cookies without adequate validation or integrity verification.
  • Trigger conditions: The vulnerability is only reachable when an application has explicitly configured cookie-based state persistence: RadPersistenceManager using CookieStateStorageProvider, or RadDockLayout with LayoutPersistenceRepositoryType set to Cookies. These are non-default but supported configurations present in real-world deployments.
  • Attack vector: An unauthenticated remote attacker submits a crafted HTTP request carrying a malicious serialized payload in the relevant cookie. No user interaction and no prior authentication are required.
  • Impact: Successful exploitation achieves full remote code execution on the server, resulting in complete compromise of confidentiality, integrity, and availability (C:H/I:H/A:H).

Affected software

  • Progress Telerik UI for ASP.NET AJAX versions 2013.1.220 through 2026.2.519 (all releases prior to 2026.2.708)

Severity

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

Mitigation and recommended actions

  • Immediate (recommended): Upgrade to Telerik UI for ASP.NET AJAX v2026.2.708 (2026 Q2 SP1) or later, which contains the vendor-provided fix.
  • Interim workarounds (if immediate patching is not possible):
    • Do not configure RadPersistenceManager with CookieStateStorageProvider. Switch to server-side, database, or session-based persistence instead.
    • Ensure RadDockLayout does not use cookie-based persistence (LayoutPersistenceRepositoryType should not be set to Cookies).

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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