CVE-2026-13189 in Telerik UI for ASP.NET AJAX
Summary
by MITRE • 07/22/2026
In Progress® Telerik® UI for AJAX prior to v2026.2.708, insufficient validation of the language parameter in the spell check handler may allow an attacker to influence server-side file path resolution and trigger unintended server-side requests.
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Analysis
by VulDB Data Team • 07/22/2026
The vulnerability exists within In Progress Telerik UI for AJAX framework version prior to v2026.2.708 where the spell check handler fails to properly validate the language parameter, creating a potential server-side path traversal or arbitrary file access condition. This flaw stems from inadequate input sanitization and validation mechanisms that should have prevented malicious language parameter values from being processed without proper authorization checks.
The technical implementation of this vulnerability allows attackers to manipulate the language parameter in the spell check handler endpoint, potentially enabling them to influence how the server resolves file paths during spell checking operations. When the application processes user-supplied language values without sufficient validation, it may inadvertently construct file system paths that reference unintended locations or execute unauthorized operations. This type of vulnerability typically falls under CWE-22 Path Traversal and CWE-73 Path Traversal where insufficient input validation leads to unintended file system access. The attack surface is particularly concerning because spell check functionality often involves reading dictionary files or other language resources from the server filesystem.
The operational impact of this vulnerability extends beyond simple path traversal as it can enable attackers to perform unauthorized server-side requests that may lead to information disclosure, remote code execution, or denial of service conditions. Depending on the server configuration and file permissions, an attacker might be able to access sensitive files, read system resources, or even execute arbitrary commands if the spell check handler operates with elevated privileges. The vulnerability also aligns with ATT&CK technique T1059 Command and Scripting Interpreter where attackers can leverage application flaws to execute unauthorized operations on the server. This represents a critical security gap that could be exploited by threat actors to gain unauthorized access to backend systems or sensitive data stored within the application's file structure.
The recommended mitigations include implementing strict input validation for all language parameters passed to the spell check handler, ensuring that only predefined and authorized language codes are accepted. Organizations should also implement proper path sanitization techniques that prevent directory traversal sequences from being processed, and consider implementing a whitelist approach for valid language identifiers. Additionally, applying the vendor-provided security patch or upgrade to version v2026.2.708 or later will address this vulnerability at the source code level. Network segmentation and monitoring of spell check handler endpoints can provide additional layers of defense by detecting anomalous access patterns or attempts to manipulate language parameters that might indicate exploitation attempts.