CVE-2026-59866: Microsoft Kiota

Critical severity, CVSS 9.3. EPSS: 1.4% chance of exploitation in the next 30 days.

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 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 1.29.1 and 1.32.5 by GenerationConfiguration.SanitizeClientClassName and SanitizeClientNamespaceName.

Affected products

• Microsoft Kiota: from 1.30.0, before 1.31.1 (fixed in 1.31.1); before 1.29.1 (fixed in 1.29.1)

Published 2026-07-16. Last modified 2026-08-17.