How severe is CVE-2026-73851?

No CVSS score has been assigned to CVE-2026-73851 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-73851?

CVE-2026-73851 affects the following packages: Microsoft.OpenApi.Kiota (NuGet), Microsoft.OpenApi.Kiota (NuGet). Ecosystems affected: NuGet.

How do I fix CVE-2026-73851?

Update Microsoft.OpenApi.Kiota to 1.34.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73851 is resolved across your whole dependency graph.

How do I detect CVE-2026-73851 in my NuGet dependencies?

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.

How do I mitigate CVE-2026-73851 if there is no patch (or I can't update yet)?

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 does O3 Security protect against CVE-2026-73851?

O3 pinpoints whether CVE-2026-73851 is reachable in your code and exactly where to fix it, then blocks exploitation in production at runtime until the patched version is deployed.

Is CVE-2026-73851 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-73851 yet. This does not mean the vulnerability cannot be exploited — absence of public exploits does not imply safety. Apply the recommended fix and use O3 Security to monitor your exposure.

What type of vulnerability is CVE-2026-73851?

CVE-2026-73851 is classified as Path Traversal (CWE-22), CWE-829 (CWE-829). These weakness types describe the underlying flaw category, which helps determine the potential impact and the right class of mitigation. This is a high-impact weakness class that often enables remote code execution or data exposure.

When was CVE-2026-73851 published, and has it been updated?

CVE-2026-73851 was published on August 17, 2026 and was last updated on August 19, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

CVE-2026-73851: Microsoft.OpenApi.Kiota

Exploitation Status

No confirmed exploitation observed yet

CISA’s own triage has not observed active exploitation or public proof-of-concept code for this CVE as of its last assessment.

Exploitation and automatability from CISA’s SSVC triage for CVE-2026-73851.

Real-World Exposure

2 pkgs affected

.NETMicrosoft.OpenApi.Kiota.NETMicrosoft.OpenApi.Kiota

Real-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 1.34.0, an attacker who controls or tampers with the OpenAPI description consumed by Kiota can supply a file reference that resolves outside the manifest package (e.g. ../../../../etc/passwd, an absolute path, or a file:// / http(s):// URI). When the generated manifest is deployed and consumed by an AI host, this can lead to inclusion or disclosure of files outside the intended package boundary. This vulnerability is fixed in 1.29.1 and 1.34.0.

Affected Packages

2 total 2 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`Microsoft.OpenApi.Kiota`	≥ 1.30.0&&< 1.34.0	1.34.0
.NETNuGet	`Microsoft.OpenApi.Kiota`	all versions	1.29.1

Detection & mitigation playbook

Open-source dependency

Detect
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 1.34.0 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms CVE-2026-73851 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-2026-73851 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-2026-73851. Runtime protection reduces exposure until a permanent patch is applied and verified — it complements patching, it doesn't replace it.

Frequently Asked Questions

Kiota is an OpenAPI based HTTP Client code generator. Prior to 1.29.1 and 1.34.0, an attacker who controls or tampers with the OpenAPI description consumed by Kiota can supply a file reference that resolves outside the manifest package (e.g. ../../../../etc/passwd, an absolute path, or a file:// / http(s):// URI). When the generated manifest is deployed and consumed by an AI host, this can lead to inclusion or disclosure of files outside the intended package boundary. This vulnerability is fixed in 1.29.1 and 1.34.0.

O3 Security · Impact-Aware SCA

Is CVE-2026-73851 in your dependencies?

O3 detects CVE-2026-73851 across NuGet dependencies and uses function-level reachability to confirm whether the vulnerable code path is actually reachable — not just present. No false positives.

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CVE-2026-73851