{"id":"CVE-2026-59861","aliases":["GHSA-xg2h-5xr2-29jw"],"title":"Microsoft Kiota: Code Generation Literal Injection in Kiota Ruby Generator","summary":"Microsoft Kiota: Code Generation Literal Injection in Kiota Ruby Generator","severity":"high","cvss":7.5,"cwe":["CWE-94"],"vendor":"Microsoft","product":"Microsoft.OpenAPI.Kiota","ecosystem":"nuget","affected":["Microsoft.OpenAPI.Kiota < 1.32.0","Microsoft.OpenAPI.Kiota.Builder < 1.32.0"],"patched":["Microsoft.OpenAPI.Kiota 1.32.0","Microsoft.OpenAPI.Kiota.Builder 1.32.0"],"published":"2026-07-24","updated":"2026-07-24","source":"GHSA","sourceUrl":"https://github.com/advisories/GHSA-xg2h-5xr2-29jw","references":[{"url":"https://github.com/microsoft/kiota/security/advisories/GHSA-xg2h-5xr2-29jw"},{"url":"https://nvd.nist.gov/vuln/detail/CVE-2026-59861"},{"url":"https://github.com/microsoft/kiota/pull/7746"},{"url":"https://github.com/microsoft/kiota/commit/fee1b648bb4394ba7ba72de9c0ce4f2a0bad0cb6"},{"url":"https://github.com/microsoft/kiota/releases/tag/v1.32.0"},{"url":"https://github.com/advisories/GHSA-xg2h-5xr2-29jw"}],"tags":["ghsa","nuget"],"epss":0.02048,"epssPercentile":0.80368,"ingestedAt":"2026-07-24T16:33:09.913Z","slug":"CVE-2026-59861","body":"## Overview\n\nCode Generation Literal Injection in Kiota Ruby Generator Leads to Arbitrary Code Execution\n\n# Impact\n\nThe 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}, #$var, and #@var within double-quoted strings at runtime, an attacker who controls an OpenAPI specification file can inject arbitrary Ruby code into generated model classes.\n\n# Who is impacted\n\nDevelopers using Kiota to generate Ruby API clients from external or untrusted OpenAPI specifications\nTeams with CI/CD pipelines configured to automatically regenerate client code from remote specs\nApplications that deploy generated Ruby code to production servers\n\n# Vulnerability details\n\nAffected component: CodeMethodWriter.cs\nRoot cause: The shared SanitizeForQuotedLiteral() function in Writers/StringExtensions.cs does not escape the # character\n\n# Attack vectors\n\nOpenAPI default fields in schema properties\nProperty wire-name hash keys in deserializer/serializer methods\nAny schema-derived string embedded in Ruby double-quoted literals\nSeverity: Critical when generated code reaches production; High for CI/CD environments with access to production secrets; Medium for public third-party specs; Low for developer-controlled specs.\n\n# Patches\n\nhttps://github.com/microsoft/kiota/pull/7746\n\n# Workarounds\n\nIf you cannot upgrade immediately:\n\n1. Audit and sanitize OpenAPI specifications: Review all OpenAPI specification files for any default values or property names containing the # character. Remove or replace any suspicious strings before code generation.\n1. Code review of generated files: Implement mandatory code review of all generated Ruby files before merging into any branch. Look for double-quoted strings containing #{, #$, or #@ patterns.\n1. 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.\n1. Isolate generated code from production: Do not deploy generated Ruby models to production environments unless the specification source has been verified and reviewed.\n1. 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).\n\n# Remediation\n\nUpgrade Kiota to 1.32.0 or later.\nRegenerate/refresh existing generated clients as a precaution:\n\n```shell\nkiota update\n```\n\nRefreshing generated clients ensures previously generated vulnerable code is replaced with hardened output.\n\n## Affected packages\n\n- `Microsoft.OpenAPI.Kiota < 1.32.0`\n- `Microsoft.OpenAPI.Kiota.Builder < 1.32.0`\n\n## Remediation\n\nUpgrade to a patched release:\n\n- `Microsoft.OpenAPI.Kiota 1.32.0`\n- `Microsoft.OpenAPI.Kiota.Builder 1.32.0`","depth":"twilight","depthScore":42,"depthScoreParts":{"impact":41.3,"likelihood":0.4,"exploitation":0,"ransomware":0},"changes":[]}