Kiota: Code Generation Literal Injection in Kiota Ruby Generator

CISA KEV is observed exploitation evidence. FIRST EPSS is a dated prediction of exploitation in the next 30 days. Missing scores are unknown. This collector requests predictions only for explicit CVE aliases in the public NuGet archive; Microsoft release views retain their existing prediction scope.

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.32.0, Kiota's Ruby generator embedded OpenAPI default fields, property names, and other schema-derived strings through CodeMethodWriter.cs and SanitizeForQuotedLiteral() in Writers/StringExtensions.cs into Ruby double-quoted literals without escaping #, allowing attacker-controlled #{expr}, #$var, or #@var interpolation markers to inject arbitrary Ruby code into generated model classes. This issue is fixed in version 1.29.1 and 1.32.0.

Source published

16 Jul 2026 14:36:32 UTC

Source modified

17 Aug 2026 15:02:02 UTC

Observed here

23 Oct 2026 15:48:27 UTC

Source terms

CVE Program Terms of Use

Original source record · Cite this exact observation · Complete original publisher JSON

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CVSS 3.1 · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.32.0, Kiota's Ruby generator embedded OpenAPI default fields, property names, and other schema-derived strings through CodeMethodWriter.cs and SanitizeForQuotedLiteral() in Writers/StringExtensions.cs into Ruby double-quoted literals without escaping #, allowing attacker-controlled #{expr}, #$var, or #@var interpolation markers to inject arbitrary Ruby code into generated model classes. This issue is fixed in version 1.29.1 and 1.32.0.

Source published

16 Jul 2026 15:16:35 UTC

Source modified

24 Oct 2026 21:10:00 UTC

Observed here

25 Oct 2026 14:19:22 UTC

Source terms

NIST NVD usage terms; underlying source attribution retained

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: nvd · NIST NVD usage terms; underlying source attribution retained. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS 3.1 · [email protected] · Secondary · 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Code Generation Literal Injection in Kiota Ruby Generator Leads to Arbitrary Code Execution # Impact The Kiota Ruby code generator is vulnerable to a code generation literal injection attack. The generator embeds string values from OpenAPI default fields and property names directly into Ruby double-quoted string literals without properly escaping the # character. Since Ruby evaluates string interpolation expressions like #{expr}, #$var, and #@var within double-quoted strings at runtime, an attacker who controls an OpenAPI specification file can inject arbitrary Ruby code into generated model classes. # Who is impacted Developers using Kiota to generate Ruby API clients from external or untrusted OpenAPI specifications Teams with CI/CD pipelines configured to automatically regenerate client code from remote specs Applications that deploy generated Ruby code to production servers # Vulnerability details Affected component: CodeMethodWriter.cs Root cause: The shared SanitizeForQuotedLiteral() function in Writers/StringExtensions.cs does not escape the # character # Attack vectors OpenAPI default fields in schema properties Property wire-name hash keys in deserializer/serializer methods Any schema-derived string embedded in Ruby double-quoted literals Severity: Critical when generated code reaches production; High for CI/CD environments with access to production secrets; Medium for public third-party specs; Low for developer-controlled specs. # Patches https://github.com/microsoft/kiota/pull/7746 # Workarounds If you cannot upgrade immediately: 1. Audit and sanitize OpenAPI specifications: Review all OpenAPI specification files for any default values or property names containing the # character. Remove or replace any suspicious strings before code generation. 1. Code review of generated files: Implement mandatory code review of all generated Ruby files before merging into any branch. Look for double-quoted strings containing #{, #$, or #@ patterns. 1. Restrict specification sources: Only consume OpenAPI specifications from trusted internal sources. Avoid automatic code generation from external or third-party APIs until this patch is applied. 1. Isolate generated code from production: Do not deploy generated Ruby models to production environments unless the specification source has been verified and reviewed. 1. Manual escaping (temporary): If regeneration is not possible, manually inspect and edit generated files to escape any # characters in string literals (replace # with \# in double-quoted strings). # Remediation Upgrade Kiota to 1.29.1, 1.32.0, or later. Regenerate/refresh existing generated clients as a precaution: ```shell kiota update ``` Refreshing generated clients ensures previously generated vulnerable code is replaced with hardened output.

Source published

24 Jul 2026 15:44:32 UTC

Source modified

17 Aug 2026 15:00:07 UTC

Observed here

23 Oct 2026 16:01:25 UTC

Source terms

GitHub Advisory Database · CC-BY-4.0

Original source record · Cite this exact observation · Complete original publisher JSON

This view projects the publisher's source fields for reading; the original JSON retains additional fields and CVE enrichment containers. Attribution: osv · GitHub Advisory Database · CC-BY-4.0. Source text is retained; field grouping and change labels are provided by ChangeIntel.

CVSS_V3 · CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H

Publisher rating · HIGH