Path Traversal in Telerik UI AJAX Persistence Storage

In Progress® Telerik® UI for AJAX prior to v2026.2.708, a path traversal vulnerability in the file-based persistence storage provider can be exploited when the storage key is derived from user-controlled input, enabling attacker-controlled deserialization and remote code execution.

Casky was already ahead

This CVE exploits attack patterns that Casky's 351matched skills already investigate — long before this vulnerability was disclosed. Claude's reasoning model maps these techniques to MITRE ATT&CK, so practitioners who ran these skills have already seen the threat behaviour in their findings.

Analysis

This vulnerability affects Progress Telerik UI for AJAX versions prior to v2026.2.708 and represents a critical supply chain risk for organizations using this widely-deployed web framework. The flaw exists in the file-based persistence storage provider, where insufficient path validation allows attackers to traverse directory structures when storage keys are derived from user-controlled input. By manipulating these keys, attackers can write malicious serialized objects to arbitrary file system locations, which are then deserialized during subsequent application operations—leading directly to remote code execution. Organizations using affected Telerik versions in production environments face immediate risk, particularly in scenarios where user input influences storage operations.

Casky's 351 matching skills leverage Claude AI's extended reasoning to detect the attack patterns mapped to MITRE ATT&CK TA0001 (Initial Access) and TA0007 (Discovery). Practitioners using the platform would identify indicators across multiple attack stages: reconnaissance patterns where attackers probe for Telerik framework versions and storage configurations (TA0007), followed by exploitation attempts involving unusual path traversal sequences in HTTP requests (CWE-22 patterns like "../" or URL encoding variants). Claude's reasoning engine correlates these attack chains, flagging suspicious serialization activities, unexpected file writes outside intended directories, and process execution anomalies that follow deserialization—enabling security teams to detect both active exploitation and post-compromise persistence mechanisms before damage occurs.

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Casky Risk Score

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EPSS Probability

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Shodan Exposure

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GreyNoise Signal

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Composite risk scoring from EPSS, CISA KEV, Shodan, and GreyNoise — 21 security APIs correlated into a single Casky Risk Score. Coming in Casky Pro. Join early access →

351 Casky skills cover this attack pattern

These skills use Claude AI's reasoning model to surface findings in the same attack categories as CVE-2026-13186.

Abuse of Public-Facing API: Mobile API Abuse

mobile security · low

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abusing-dpapi-for-credential-access

red teaming · high

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abusing-shadow-credentials-for-privesc

red teaming · high

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MITRE ATT&CK Techniques

TA0001 TA0007

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