CVE-2026-13184 in Telerik UI for ASP.NET AJAX
Summary
by MITRE • 07/22/2026
In Progress® Telerik® UI for AJAX prior to v2026.2.708, when Telerik.Upload.ConfigurationHashKey is absent and machineKey is not explicitly configured, upload metadata integrity protection may fall back to a predictable default key, enabling attackers to forge protected upload metadata and unlock further exploit chains.
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Analysis
by VulDB Data Team • 07/22/2026
The vulnerability in Progress® Telerik® UI for AJAX versions prior to v2026.2.708 represents a critical security flaw related to upload metadata integrity protection mechanisms. This issue stems from the application's fallback behavior when specific cryptographic configuration parameters are missing, creating a predictable default key scenario that undermines the security of file upload operations. The vulnerability specifically affects systems where Telerik.Upload.ConfigurationHashKey is absent and machineKey is not explicitly configured, leaving the framework to rely on insecure default values.
The technical flaw exploits the absence of proper cryptographic key management within the Telerik framework's upload functionality. When the ConfigurationHashKey parameter is missing from the application configuration and no explicit machineKey is defined, the system defaults to using a predictable cryptographic key that can be easily determined by attackers. This predictable fallback mechanism allows malicious actors to compute valid hash values for modified upload metadata, effectively bypassing the intended integrity protection measures. The vulnerability operates at the core of the framework's security model, where upload metadata should remain tamper-proof through cryptographic hashing but instead becomes vulnerable due to improper key handling.
The operational impact of this vulnerability extends beyond simple file upload manipulation and can enable more sophisticated attack chains. Attackers who successfully forge upload metadata can potentially bypass access controls, manipulate file processing workflows, and execute arbitrary code within the application context. This weakness provides a potential entry point for privilege escalation attacks or data manipulation scenarios where attackers can alter file properties, inject malicious content, or disrupt normal application functionality. The vulnerability is particularly concerning in environments where file uploads are processed with elevated privileges or where uploaded files trigger automated processing functions.
Security professionals should implement multiple mitigation strategies to address this vulnerability effectively. The primary recommendation involves explicitly configuring both Telerik.Upload.ConfigurationHashKey and machineKey parameters within the application configuration to ensure cryptographic randomness and prevent fallback to predictable defaults. Organizations must also conduct thorough security audits of their Telerik framework implementations to identify systems running vulnerable versions and verify proper cryptographic key management practices. Additionally, implementing network-level monitoring for suspicious upload patterns and maintaining up-to-date framework versions through proper patch management procedures are essential defensive measures.
This vulnerability aligns with CWE-327 (Use of a Broken or Risky Cryptographic Algorithm) and CWE-310 (Cryptographic Issues) categories, demonstrating poor implementation of cryptographic security controls. From an attacker perspective, this issue maps to ATT&CK technique T1566.001 (Phishing: Spearphishing Attachment) and T1203 (Exploitation for Client Execution) where the predictable key allows for more sophisticated exploitation chains. The vulnerability also reflects broader concerns about insecure default configurations that can be exploited when proper security hardening practices are not followed, making it a significant concern for compliance frameworks like NIST 800-53 and ISO 27001 that require robust cryptographic controls and secure configuration management.
Organizations should prioritize immediate remediation by updating to Telerik UI for AJAX version 2026.2.708 or later, which includes proper cryptographic key handling mechanisms. The update process must ensure that all deployment environments receive the patched version and that existing configurations are reviewed to eliminate reliance on insecure default values. Regular security assessments should include verification of cryptographic configuration parameters, and development teams should implement secure coding practices that explicitly define cryptographic keys rather than relying on framework defaults. This vulnerability serves as a reminder of the critical importance of proper cryptographic key management and the potential consequences when security controls fail due to inadequate configuration practices.