CVE-2026-59866 in Kiota
Summary
by MITRE • 07/16/2026
Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.32.5, Kiota emitted x-ms-kiota-info clientClassName and clientNamespaceName values without identifier or path sanitization as both generated client class or namespace names and generated output path components when `kiota generate` ran without -c/--class-name, allowing an attacker-controlled or compromised OpenAPI description to write generated source outside the -o output directory and inject arbitrary text into generated class or namespace declarations. This issue is fixed in version 1.32.5 by GenerationConfiguration.SanitizeClientClassName and SanitizeClientNamespaceName.
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Analysis
by VulDB Data Team • 07/16/2026
The vulnerability in Kiota versions prior to 1.32.5 represents a critical security flaw that enables path traversal and code injection attacks through improper input sanitization during the client generation process. This issue arises from the absence of identifier or path sanitization when processing x-ms-kiota-info clientClassName and clientNamespaceName values from OpenAPI descriptions. The vulnerability specifically impacts the kiota generate command when executed without explicit class name parameters, creating a dangerous attack surface where malicious or compromised OpenAPI specifications can manipulate the generation output.
The technical flaw stems from insufficient validation of user-controlled input during the code generation workflow. When Kiota processes OpenAPI documents containing x-ms-kiota-info metadata, it directly incorporates clientClassName and clientNamespaceName values into generated source code without proper sanitization mechanisms. This allows attackers to inject malicious path components or arbitrary text that gets written to files outside the designated output directory specified by the -o flag. The vulnerability creates a path traversal condition where generated files can be placed in unintended locations on the filesystem, potentially overwriting existing critical files or creating malicious code in unexpected directories.
The operational impact of this vulnerability extends beyond simple file placement issues to include potential code injection attacks that could compromise the integrity of generated client libraries. Attackers could manipulate the generated class or namespace declarations by injecting malicious identifiers, leading to runtime errors or potentially exploitable code patterns in the generated clients. This represents a direct violation of the principle of least privilege and can result in unauthorized file system modifications, code corruption, or even remote code execution if the generated clients are subsequently compiled and executed in environments with elevated privileges.
The fix implemented in version 1.32.5 addresses this vulnerability through the introduction of GenerationConfiguration.SanitizeClientClassName and SanitizeClientNamespaceName properties that enforce proper input sanitization before incorporating user-controlled values into generated code. This remediation aligns with industry best practices for preventing path traversal and injection attacks, specifically addressing CWE-22 Path Traversal and CWE-74 Improper Neutralization of Special Elements in Output Used by a Downstream Component. The solution follows ATT&CK technique T1059.006 Command and Scripting Interpreter: Python, which emphasizes the importance of input validation in preventing code injection vulnerabilities.
Security practitioners should recognize this vulnerability as part of broader software supply chain security concerns, particularly when dealing with automated code generation tools that process external specifications. The issue highlights the critical need for proper input validation in development tools, especially those operating in untrusted environments where OpenAPI documents might be provided by third parties or could be compromised. Organizations using Kiota should immediately upgrade to version 1.32.5 or later and implement additional monitoring of generated code outputs for unexpected file placements or malformed class declarations that could indicate exploitation attempts.