CyberSecBulletin
CVE-2026-13183NVD status: Analyzed

Telerik UI for ASP.NET AJAX: Observable Timing Discrepancy

Published Updated By the CyberSecBulletin desk

CVE-2026-13183 is a high-severity observable timing discrepancy vulnerability in Telerik UI for ASP.NET AJAX from Progress Software, with a CVSS 3.1 base score of 7.5 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 2026.2.708 as the first without the flaw, so updating Telerik UI for ASP.NET AJAX to that release or later removes the exposure. There is no confirmed exploitation so far. EPSS estimates a 0.5% chance of exploitation within 30 days, which is low compared with other CVEs.

Next patch cycle

High severity with no evidence of exploitation so far.

What to do

  1. Update Telerik UI for ASP.NET AJAX to 2026.2.708 or a later version.
  2. Read the advisory on telerik.com for workarounds and exact fixed builds.
  3. Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.

Affected products and versions

VendorProductAffected versionsFixed in
Progress SoftwareTelerik UI for ASP.NET AJAX2010.1.309 up to, but not including, 2026.2.7082026.2.708

Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.

How the severity score breaks down

Attack vector
NetworkCan be exploited remotely over a network, including the internet.
Attack complexity
LowNo special conditions are needed; the attack works reliably.
Privileges required
NoneNo account or login is needed.
User interaction
NoneNo action by a victim is required.
Scope
UnchangedImpact stays within the vulnerable component.
Confidentiality
HighAll data handled by the component can be read.
Integrity
NoneNothing can be modified.
Availability
NoneAvailability is not affected.

Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:N/A:N. Scored by CNA (progress.com).

Official description

In Progress® Telerik® UI for AJAX prior to v2026.2.708, RadAsyncUpload upload metadata processing may leak cryptographic validity through measurable timing differences, enabling remote attackers to recover protected metadata values.

Source: the CVE record as published by its numbering authority, via NVD and CVE.org.

The underlying weakness: Observable Timing Discrepancy

Two separate operations in a product require different amounts of time to complete, in a way that is observable to an actor and reveals security-relevant information about the state of the product, such as whether a particular operation was successful or not.

More Observable Timing Discrepancy vulnerabilities (CWE-208)

Timeline

  1. CVE record published.
  2. CISA published its SSVC assessment (exploitation: none, automatable: yes, technical impact: partial).
  3. Record last changed materially (score, affected products, status or references).

References

Other vulnerabilities in Telerik UI for ASP.NET AJAX

All Telerik UI for ASP.NET AJAX vulnerabilities

Recent Observable Timing Discrepancy vulnerabilities

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