Arbitrary Code Injection Affecting microsoft.openapi.kiota package, versions [,1.32.3)
Threat Intelligence
The probability is the direct output of the EPSS model, and conveys an overall sense of the threat of exploitation in the wild. The percentile measures the EPSS probability relative to all known EPSS scores. Note: This data is updated daily, relying on the latest available EPSS model version. Check out the EPSS documentation for more details.
Do your applications use this vulnerable package?
In a few clicks we can analyze your entire application and see what components are vulnerable in your application, and suggest you quick fixes.
Test your applications- Snyk IDSNYK-DOTNET-MICROSOFTOPENAPIKIOTA-18021356
- published20 Jul 2026
- disclosed16 Jul 2026
- creditthegr1ffyn
Introduced: 16 Jul 2026
NewCVE-2026-59860 (opens in a new tab)How to fix?
Upgrade Microsoft.OpenApi.Kiota to version 1.32.3 or higher.
Overview
Affected versions of this package are vulnerable to Arbitrary Code Injection through the C# doc-comment generation in CSharpConventionService and OpenApiUrlTreeNodeExtensions. An attacker can inject executable C# into generated clients by supplying description, externalDocs label, or link text containing newline or Unicode line-terminator characters that break out of the /// comment context. When a developer or CI builds the generated client, the injected text is compiled as source code, which can lead to arbitrary code execution in the resulting application. The issue affects generated C# documentation comments emitted from untrusted or tampered OpenAPI descriptions.
Notes
- The vulnerable doc-comment sinks are in the C# generator path, so the issue is in generated clients rather than the runtime parser or OpenAPI ingestion itself.
- The injected payload is only compiled when the generated client source is built, so exploitation depends on a build step consuming the generated code from an untrusted or tampered OpenAPI description.
Workarounds
- Only generate clients from trusted, integrity-protected OpenAPI descriptions; avoid using untrusted or tampered API descriptions as input to generation.