CVE-2026-71262 in IoTSharp
Summary
by MITRE • 08/05/2026
IoTSharp BlobStorageController.cs lacks the [Authorize] attribute applied to every other controller in the application (DevicesController, CustomersController, TenantsController, etc.), and no global authorization FallbackPolicy is configured in Startup.cs, leaving its Upload/Download/List/Modify/Delete endpoints reachable by unauthenticated remote attackers. The path/filename parameters passed to these endpoints (e.g. `_blob.WriteFileAsync($"{path}/{formFile.FileName}", ...)`) are used without sanitization, enabling path traversal that allows writing, reading, modifying, and deleting arbitrary files outside the intended blob storage directory, including web-accessible paths that can be leveraged for remote code execution via webshell upload.
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Analysis
by VulDB Data Team • 08/05/2026
The vulnerability identified in IoTSharp's BlobStorageController.cs represents a critical authorization flaw that undermines the entire security posture of the application. This controller serves as an entry point for file operations without proper authentication mechanisms, creating an attack surface that exposes core functionality to unauthenticated remote adversaries. The absence of the [Authorize] attribute on this specific controller while all other controllers in the application properly enforce authentication highlights a significant inconsistency in the security implementation. This oversight creates a dangerous gap where attackers can directly interact with blob storage operations through endpoints designed for upload, download, list, modify, and delete functions without requiring any form of authentication or access control validation.
The technical exploitation of this vulnerability relies on path traversal attacks that occur due to insufficient input sanitization of path and filename parameters. When the application processes user-supplied file paths through methods like `_blob.WriteFileAsync($"{path}/{formFile.FileName}", ...)`, it fails to validate or sanitize these inputs before using them in file system operations. This lack of sanitization creates a classic path traversal vulnerability that allows attackers to manipulate directory paths and access files outside the intended blob storage boundaries. The vulnerability can be exploited across multiple attack vectors including writing malicious files, reading sensitive data from arbitrary locations, modifying existing files, and deleting critical application components.
The operational impact of this vulnerability extends far beyond simple unauthorized file access. Attackers can leverage the path traversal capabilities to upload webshells or other malicious payloads into web-accessible directories, effectively gaining remote code execution capabilities within the application environment. This represents a severe escalation from mere data exposure to full system compromise, as demonstrated by the potential for webshell deployment through the vulnerable file operations. The vulnerability affects all file system operations within the blob storage controller, making it particularly dangerous since attackers can perform any operation on the underlying file system without authentication.
Security standards such as CWE-22 Path Traversal and CWE-798 Use of Hard-coded Credentials directly apply to this situation, with the missing authorization mechanism representing a failure in proper access control implementation. The ATT&CK framework categorizes this vulnerability under T1059 Command and Scripting Interpreter and T1566 Phishing, as attackers can use the webshell upload capability to establish persistent access and execute commands on the compromised system. The absence of global authorization fallback policy configuration in Startup.cs further compounds the issue by creating a systemic failure in authentication enforcement that allows multiple controllers to operate without proper security boundaries.
Mitigation strategies should include immediate implementation of the [Authorize] attribute on the BlobStorageController.cs file, combined with comprehensive input validation and sanitization for all path parameters. The application should enforce global authorization policies through Startup.cs configuration to ensure consistent access control across all controllers. Additional protective measures include implementing strict path validation that prevents directory traversal attempts, establishing proper file system access controls, and configuring appropriate logging for all blob storage operations. Network-level protections such as firewall rules and API gateway security controls should also be implemented to limit exposure of these endpoints. Regular security testing including penetration testing and code reviews should be conducted to identify similar authorization gaps in other parts of the application that might present similar vulnerabilities.