CVE-2026-59867 is a high-severity (CVSS 7.1) Path Traversal vulnerability in Microsoft.OpenApi.Kiota. O3 Security confirms whether CVE-2026-59867 is actually reachable in your code before you act, and blocks exploitation at runtime until you patch.
Kiota: Generation-time SSRF + remote/local file inclusion via unrestricted $ref
Real-World Exposure
Microsoft.OpenApi.Kiota.NETMicrosoft.OpenApi.Kiota.Builder.NETMicrosoft.OpenApi.Kiota.NETMicrosoft.OpenApi.Kiota.BuilderReal-time download stats are indexed for npm and PyPI packages. This vulnerability affects NuGet packages — download data is not available via public APIs for these ecosystems.
Description
Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.32.5, Kiota resolved OpenAPI $ref values by fetching remote http(s) URLs and reading local absolute or out-of-tree file paths, allowing kiota generate on an attacker-controlled or attacker-influenced description to perform build-time SSRF, remote file inclusion, and local file inclusion by inlining external schemas such as REMOTE_KIOTA_PROP or Leaked into generated clients. This issue is fixed in version 1.29.1 and 1.32.5 by AllowedExternalOriginsStreamLoader and the --allowed-external-origins option.
Affected Packages
| Ecosystem | Package | Vulnerable range | Fix |
|---|---|---|---|
| .NETNuGet | Microsoft.OpenApi.Kiota | ≥ 1.30.0&&< 1.32.5 | 1.32.5 |
| .NETNuGet | Microsoft.OpenApi.Kiota.Builder | ≥ 1.30.0&&< 1.32.5 | 1.32.5 |
| .NETNuGet | Microsoft.OpenApi.Kiota | all versions | 1.29.1 |
| .NETNuGet | Microsoft.OpenApi.Kiota.Builder | all versions | 1.29.1 |
Detection & mitigation playbook
Open-source dependencyDetect
Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.OpenApi.Kiota. O3's reachability analysis confirms whether the vulnerable code path is actually invoked in your application, so you act on real exposure instead of every transitive match.
Fix
Update Microsoft.OpenApi.Kiota to 1.32.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-59867 is resolved across your whole dependency graph.
Workarounds
If you can't upgrade right away: gate or disable the affected feature, validate untrusted input at the boundary, and avoid passing attacker-controlled data into the vulnerable path. O3's runtime protection blocks exploitation in production as an interim safeguard until the upgrade lands.
How O3 protects you
O3 pinpoints whether CVE-2026-59867 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.
Tailored to CVE-2026-59867. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.
Frequently Asked Questions
Is CVE-2026-59867 in your dependencies?
O3 detects CVE-2026-59867 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.