{"id":"GHSA-3hrf-2gc2-mx32","revision":"b6e2831a4fea41c28aabf6070d152a5a","records":[{"revision":"b6e2831a4fea41c28aabf6070d152a5a","observedAt":"2026-10-23T16:01:25.029+00:00","statement":{"source":"osv","id":"GHSA-3hrf-2gc2-mx32","aliases":["CVE-2026-59860"],"title":"Microsoft Kiota: XML Doc-Comment Newline Breakout Code Injection","description":"### Summary\n\nKiota versions **prior to 1.32.3 and 1.29.1** are affected by a code-generation injection vulnerability in the C# XML documentation-comment sink (the `description`, `externalDocs` label, and `externalDocs` link fields emitted as `/// …` comments).\n\nWhen text from an OpenAPI description is written into single-line XML doc comments without stripping newline and Unicode line-terminator characters, an attacker can break out of the `///` comment line and inject additional code into generated C# clients.\n\n## Impact and Preconditions\n\nThis issue is only practically exploitable when:\n\n1.  the OpenAPI description used for generation is from an **untrusted source**, or\n2.  a normally trusted OpenAPI description has been **compromised/tampered with**.\n\nThe injected code is compiled (and may execute) when the developer or CI **builds** the generated client. If you only generate from trusted, integrity-protected API descriptions, risk is significantly reduced.\n\n## Affected Versions\n\n- **Affected:** all versions **< 1.29.1**, **>= 1.30.0, < 1.32.3**\n- **Fixed: 1.29.1, 1.32.3,** and later\n\n## Illustrative Exploit Example\n\n### Example OpenAPI fragment (malicious description)\n\n```yaml\nopenapi: 3.0.1\ninfo:\n  title: Exploit Demo\n  version: 1.0.0\n  description: |-\n    Legitimate summary text\n    public static class Pwned { static Pwned() { System.Diagnostics.Process.Start(\"calc.exe\"); } }\n```\n\nThe newline inside `description` (also exploitable via `\\r`, U+0085, U+2028, U+2029) terminates the doc-comment line.\n\n### Example generated C# snippet before fix (illustrative)\n\n```csharp\n/// Legitimate summary text\npublic static class Pwned { static Pwned() { System.Diagnostics.Process.Start(\"calc.exe\"); } }\n```\n\nThe injected payload escapes the intended `///` comment context and introduces attacker-controlled statements in generated code.\n\n> Note: this exploit is not limited to the `description` field, but may also impact the `externalDocs` label and link text and other doc-comment-derived locations.\n\n## Remediation\n\n1.  Upgrade Kiota to **1.32.3 or later**.\n2.  Regenerate/refresh existing generated clients as a precaution:\n\nRefreshing generated clients ensures previously generated vulnerable code is replaced with hardened output. The fix (PR microsoft/kiota#7831) strips `\\r`, `\\n`, `\\u0085`, `\\u2028`, `\\u2029` (and normalizes tabs) from description, label, and link text before emitting doc comments.","state":0,"publishedAt":"2026-07-24T15:30:47+00:00","modifiedAt":"2026-08-17T15:00:08.078074+00:00","affected":[{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota","ranges":[{"type":"ECOSYSTEM","events":[{"kind":"introduced","version":"1.30.0"},{"kind":"fixed","version":"1.32.3"}]}],"versions":["1.30.0","1.31.0","1.31.1","1.32.0","1.32.1","1.32.2"],"rawVersionEvidence":null},{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota.Builder","ranges":[{"type":"ECOSYSTEM","events":[{"kind":"introduced","version":"1.30.0"},{"kind":"fixed","version":"1.32.3"}]}],"versions":[],"rawVersionEvidence":null},{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota","ranges":[{"type":"ECOSYSTEM","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"1.29.1"}]}],"versions":["0.1.0-preview","0.1.1-preview","0.1.2-preview","0.1.3-preview","0.10.0-preview","0.11.0-preview","0.11.1-preview","0.2.0-preview","0.2.1-preview","0.3.0-preview","0.4.0-preview","0.5.0-preview","0.5.1-preview","0.6.0-preview","0.7.1-preview","0.8.3-preview","0.9.0-preview","1.0.0","1.0.1","1.1.0","1.1.1","1.1.2","1.1.3","1.10.0","1.10.1","1.11.0","1.11.1","1.12.0","1.13.0","1.14.0","1.15.0","1.16.0","1.17.0","1.18.0","1.19.0","1.19.1","1.2.0","1.2.1","1.20.0","1.21.0","1.22.0","1.22.1","1.22.2","1.22.3","1.23.0","1.24.0","1.24.1","1.24.2","1.24.3","1.25.1","1.26.0","1.26.1","1.27.0","1.28.0","1.29.0","1.3.0","1.4.0","1.5.0","1.5.1","1.6.1","1.7.0","1.8.0","1.8.1","1.8.2","1.9.0","1.9.1"],"rawVersionEvidence":null},{"ecosystem":"NuGet","name":"Microsoft.OpenApi.Kiota.Builder","ranges":[{"type":"ECOSYSTEM","events":[{"kind":"introduced","version":"0"},{"kind":"fixed","version":"1.29.1"}]}],"versions":["0.2.0-preview","0.3.0-preview","0.4.0-preview","0.5.0-preview","0.5.1-preview","0.6.0-preview","0.7.1-preview","1.0.0","1.0.1","1.1.0","1.1.1","1.1.2","1.1.3","1.10.0","1.10.1","1.11.0","1.11.1","1.12.0","1.13.0","1.14.0","1.15.0","1.16.0","1.17.0","1.18.0","1.19.0","1.19.1","1.2.0","1.2.1","1.20.0","1.21.0","1.22.0","1.22.1","1.22.2","1.22.3","1.23.0","1.3.0","1.4.0","1.5.0","1.5.1","1.6.1","1.7.0","1.8.0","1.8.1","1.8.2","1.9.0","1.9.1"],"rawVersionEvidence":null}],"metrics":[{"system":"CVSS_V4","vector":"CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N","score":null,"severity":null},{"system":"Publisher rating","vector":null,"score":null,"severity":"HIGH"}],"references":["https://github.com/microsoft/kiota/security/advisories/GHSA-3hrf-2gc2-mx32","https://nvd.nist.gov/vuln/detail/CVE-2026-59860","https://github.com/microsoft/kiota/pull/7831","https://github.com/microsoft/kiota/commit/ebb632db90aa8e3c20949337d9faa2720d64ca44","https://github.com/microsoft/kiota","https://github.com/microsoft/kiota/releases/tag/v1.32.3"],"sourceUrl":"https://github.com/advisories/GHSA-3hrf-2gc2-mx32","license":"GitHub Advisory Database · CC-BY-4.0","key":"osv:GHSA-3hrf-2gc2-mx32","identifiers":["GHSA-3hrf-2gc2-mx32","CVE-2026-59860"]},"retained":false,"historicalAffected":[]}],"coverage":[]}