CVE-2026-106151 in Kendo UI for jQuery
Summary
by MITRE • 10/15/2026
In Progress® Kendo® UI for jQuery versions starting with 2012.2.710 and prior to 2026.3.1015, the Validator decodes validation messages from data-msg-* attributes and parses the resulting text as HTML. An attacker who can modify a validation message can cause HTML that was correctly escaped in the page attribute to become active markup, including event handlers, when the user triggers validation. Successful exploitation can execute JavaScript in a user's browser and compromise the confidentiality and integrity of data accessible to the affected application. This issue is fixed in version 2026.3.1015.
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Analysis
by VulDB Data Team • 10/15/2026
The vulnerability identified in Progress Kendo UI for jQuery represents a classic Cross-Site Scripting (XSS) flaw rooted in improper input validation and output encoding mechanisms within the framework's Validator component. Specifically, versions starting from 2012.2.710 up to but not including version 2026.3.1015 contain a logic error where the library decodes HTML entities found in data-msg-* attributes before parsing them as raw HTML for display during validation feedback. This behavior deviates from secure coding practices which dictate that user-supplied or dynamically generated content intended for display should be treated as plain text unless explicitly trusted and sanitized through robust allow-listing mechanisms. By decoding the message string prior to insertion into the DOM, the framework inadvertently re-introduces executable script tags or event handlers that may have been previously escaped by developers attempting to mitigate XSS risks in their initial markup construction.
From a technical perspective, this flaw allows an attacker who possesses the ability to influence the content of validation messages to inject malicious JavaScript payloads directly into the user's browser context. The attack vector typically involves manipulating server-side logic or client-side configuration that populates these data attributes with untrusted input. When the end-user triggers a form submission or field blur event, causing the Kendo Validator to execute and render its error message, the decoded HTML is processed by the browser’s rendering engine as active markup rather than inert text. This results in the immediate execution of any embedded script elements, such as onload events on image tags or direct script blocks, effectively bypassing standard Content Security Policy protections if they are not strictly configured to prevent inline scripts.
The operational impact of this vulnerability is severe, primarily affecting the confidentiality and integrity of data accessible through the affected application. Successful exploitation enables session hijacking, where an attacker can steal authentication cookies or tokens stored in the browser local storage, thereby gaining unauthorized access to user accounts. Furthermore, it facilitates phishing attacks by allowing the injection of fake login forms or deceptive UI elements that mimic legitimate application interfaces, tricking users into divulging sensitive credentials. The integrity impact arises from the ability to modify page content dynamically, potentially altering transaction details or displaying false information to end-users, which can lead to significant financial loss and reputational damage for organizations relying on this framework for their web applications.
This vulnerability aligns with Common Weakness Enumeration (CWE) ID 79, known as Improper Neutralization of Input During Web Page Generation, commonly referred to as Cross-site Scripting. It also maps closely to the MITRE ATT&CK technique T1059, specifically sub-technique T1059.007 for Command and Scripting Interpretation via JavaScript. The flaw highlights a critical gap in how modern web frameworks handle dynamic content injection, emphasizing that even established libraries must be scrutinized for secure defaults regarding HTML parsing and encoding. Developers utilizing these versions are advised to upgrade immediately to version 2026.3.1015 or later, where the issue has been resolved by ensuring that validation messages are properly escaped before being rendered as HTML. Additionally, implementing strict Content Security Policy headers can provide an additional layer of defense by restricting the sources from which scripts can be executed, thereby mitigating the impact even if similar vulnerabilities exist in other components of the application stack.