Answer in brief
CVE-2026-59866 records a Critical severity (CVSS 9.3) vulnerability in Kiota: Arbitrary file write + code-injection via x-ms-kiota-info clientClassName and clientNamespaceName. The current sources do not mark it as known exploited. The current feed maps microsoft/kiota (generic), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota.Builder (nuget) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
Answer in brief
CVE-2026-59866 records a Critical severity (CVSS 9.3) vulnerability in Kiota: Arbitrary file write + code-injection via x-ms-kiota-info clientClassName and clientNamespaceName. The current sources do not mark it as known exploited. The current feed maps microsoft/kiota (generic), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota.Builder (nuget) and additional mapped packages. Check affected ranges and fixed versions before updating.
Analysis pending evidence review
HOL Guard separates source facts from reviewed analysis. See the methodology.
CVSS is 9.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps microsoft/kiota (generic), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota.Builder (nuget) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| microsoft/kiotageneric | >= 1.30.0, < 1.31.1 || < 1.29.1 | Not reported |
| Microsoft.OpenApi.Kiotanuget | >=1.30.0,<1.32.5 | 1.32.5 |
| Microsoft.OpenApi.Kiotanuget | <1.29.1 | 1.29.1 |
| Microsoft.OpenApi.Kiota.Buildernuget | <1.29.1 | 1.29.1 |
| Microsoft.OpenApi.Kiota.Buildernuget | >=1.30.0,<1.32.5 | 1.32.5 |
Published upstream
Jul 16, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 16, 2026
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.
Quoted source text, attributed separately from HOL analysis.
CVSS is 9.3. The current sources do not mark it as known exploited. Treat this as a source-backed prioritization signal, not a statement about your environment.
Analysis status
Analysis pending evidence review
Factual feed record only; HOL analysis is not approved for indexing. Read the methodology.
The current feed maps microsoft/kiota (generic), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota (nuget), Microsoft.OpenApi.Kiota.Builder (nuget) and additional mapped packages. Check affected ranges and fixed versions before updating.
| Package | Affected range | Fixed version |
|---|---|---|
| microsoft/kiotageneric | >= 1.30.0, < 1.31.1 || < 1.29.1 | Not reported |
| Microsoft.OpenApi.Kiotanuget | >=1.30.0,<1.32.5 | 1.32.5 |
| Microsoft.OpenApi.Kiotanuget | <1.29.1 | 1.29.1 |
| Microsoft.OpenApi.Kiota.Buildernuget | <1.29.1 | 1.29.1 |
| Microsoft.OpenApi.Kiota.Buildernuget | >=1.30.0,<1.32.5 | 1.32.5 |
Published upstream
Jul 16, 2026
Evidence: source:cvelist:source_dates:source-dates:recordSource modified
Aug 17, 2026
Evidence: source:cvelist:source_dates:source-dates:recordFirst seen by HOL
Jul 16, 2026
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.
Quoted source text, attributed separately from HOL analysis.