How severe is GHSA-4vv7-jj25-4gh6?

No CVSS score has been assigned to GHSA-4vv7-jj25-4gh6 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by GHSA-4vv7-jj25-4gh6?

GHSA-4vv7-jj25-4gh6 affects the following packages: Microsoft.OpenApi.Kiota (NuGet), Microsoft.OpenApi.Kiota.Builder (NuGet), Microsoft.OpenApi.Kiota (NuGet), Microsoft.OpenApi.Kiota.Builder (NuGet). Ecosystems affected: NuGet.

How do I fix GHSA-4vv7-jj25-4gh6?

Update Microsoft.OpenApi.Kiota to 1.32.5 or later, then make sure no transitive (indirect) dependency still pins the vulnerable range — O3 confirms GHSA-4vv7-jj25-4gh6 is resolved across your whole dependency graph.

How do I detect GHSA-4vv7-jj25-4gh6 in my NuGet dependencies?

Scan your dependency tree (package-lock.json, pnpm-lock.yaml, requirements.txt, go.sum, etc.) for Microsoft.OpenApi.Kiota, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.

How do I mitigate GHSA-4vv7-jj25-4gh6 if there is no patch (or I can't update yet)?

Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Is GHSA-4vv7-jj25-4gh6 actively exploited in the wild?

No public exploit code has been indexed for GHSA-4vv7-jj25-4gh6 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 is the EPSS score for GHSA-4vv7-jj25-4gh6?

GHSA-4vv7-jj25-4gh6 has an EPSS (Exploit Prediction Scoring System) score of 1.4%, placing it in the 72th percentile of all CVEs. EPSS is maintained by FIRST.org and estimates the probability that a vulnerability will be exploited in the wild within the next 30 days. This score indicates relatively lower exploitation probability, though the CVSS severity should still guide your patching priority.

What type of vulnerability is GHSA-4vv7-jj25-4gh6?

GHSA-4vv7-jj25-4gh6 is classified as Path Traversal (CWE-22), Code Injection (CWE-94). 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 GHSA-4vv7-jj25-4gh6 published, and has it been updated?

GHSA-4vv7-jj25-4gh6 was published on July 24, 2026 and was last updated on August 17, 2026. Advisory data evolves as severity scores, affected ranges, and exploit intelligence are revised — always check the latest version of the advisory before acting.

.NET NuGet

Not in CISA KEV

Microsoft Kiota: Arbitrary file write + code-injection via x-ms-kiota-info clientClassName and clientNamespaceNameGHSA-4vv7-jj25-4gh6

Fix: microsoft/kiota#7884

GHSA-4vv7-jj25-4gh6 is a Path Traversal vulnerability in Microsoft.OpenApi.Kiota. A fix is available for Microsoft.OpenApi.Kiota — see the affected versions and patch details below.

Also known asCVE-2026-59866

Published

Jul 24, 2026

Updated

Aug 17, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 17, 2026 · OSV.dev, NVD, FIRST.org (EPSS)

Exploitation Status

No confirmed exploitation observed yet

CISA assesses this as automatable — exploitation doesn’t require manual, per-target effort, which raises the odds of mass scanning and opportunistic attacks.
A successful exploit gives an attacker total control of the affected component, not partial access.
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 GHSA-4vv7-jj25-4gh6.

EPSS Exploitation Probability

via FIRST.org ↗

1.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs72th percentile — riskier than 72% of all scored CVEsHighest risk

Probability of exploitation in the next 30 days, from FIRST.org EPSS.

Real-World Exposure

4 pkgs affected

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

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

Summary

Microsoft Kiota emitted the x-ms-kiota-info extension's clientClassName or clientNamespaceName value raw, with no identifier or path sanitization, as both the generated client's class/namespace name and part of the generated output path. When kiota generate is run without -c/--class-name — the zero-config workflow that x-ms-kiota-info is explicitly designed for (the API provider supplies the names in the description so consumers don't have to) — an attacker who controls or tampers with the OpenAPI description could therefore:

(CWE-22) write the generated source file to a path outside the -o output directory — e.g. clientClassName: "/var/www/html/shell"; and
(CWE-94) inject arbitrary text into the generated class/namespace declaration, corrupting the generated client.

Confirmed on Kiota 1.32.4 (the self-contained linux-x64 release binary), i.e. after the earlier writer-sink hardening — that fix escaped property/enum/default/serialization sinks but never sanitized the provider-supplied clientClassName / clientNamespaceName.

Details

clientClassName reached two unsanitized sinks (observed in the generated C#; the same raw emission occurred for Java, Go, TypeScript, Python, and PHP):

# output FILENAME (CWE-22): clientClassName flows into the file path
clientClassName: "/abs/path/PWNED"   ->   /abs/path/PWNED.cs   (written outside -o)

# class declaration (CWE-94): clientClassName flows verbatim into the type declaration
clientClassName: 'Pwn { } public class INJECTED { } public partial class RealClient'
   ->  public partial class Pwn { } public class INJECTED { } public partial class RealClient : ... { }

clientNamespaceName reached the analogous namespace/path sinks.

Impact

A developer or CI host generating a client from an attacker-controlled or compromised OpenAPI description (without -c) could create/overwrite a generated source file at an attacker-influenced path and emit attacker-controlled text into the generated client.

This does not reach clean remote code execution: because clientClassName is reused verbatim at multiple sites (the class name and the constructor name), injected code cannot be made to compile — it breaks the build. So the code-injection vector is a generation/build-corruption (integrity/DoS), and the high-severity primitive is the file write. CWE-22 / CWE-94.

Patches

Fixed in 1.29.1 and 1.32.5 (https://github.com/microsoft/kiota/pull/7884). clientClassName and clientNamespaceName sourced from x-ms-kiota-info are now sanitized before use: GenerationConfiguration.SanitizeClientClassName strips any character outside [A-Za-z0-9_] and any invalid leading character (falling back to ApiClient), and SanitizeClientNamespaceName restricts to [A-Za-z0-9._-], collapses consecutive dots, strips invalid leading characters (falling back to ApiSdk). This removes path separators, drive/colon, .., quotes, and braces, so the values can no longer influence the output path or inject into the declaration.

Remediation

Upgrade to Kiota 1.29.1, 1.32.5, or later and regenerate affected clients.

Affected Packages

4 total 4 fixed

Ecosystem	Package	Vulnerable range	Fix
.NETNuGet	`Microsoft.OpenApi.Kiota`	≥ 1.30.0&&< 1.32.5	1.32.5`dotnet add package Microsoft.OpenApi.Kiota --version 1.32.5`
.NETNuGet	`Microsoft.OpenApi.Kiota.Builder`	≥ 1.30.0&&< 1.32.5	1.32.5`dotnet add package Microsoft.OpenApi.Kiota.Builder --version 1.32.5`
.NETNuGet	`Microsoft.OpenApi.Kiota`	all versions	1.29.1`dotnet add package Microsoft.OpenApi.Kiota --version 1.29.1`
.NETNuGet	`Microsoft.OpenApi.Kiota.Builder`	all versions	1.29.1`dotnet add package Microsoft.OpenApi.Kiota.Builder --version 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, including transitive dependencies — a direct dependency you never call can still pull in a vulnerable version.
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 GHSA-4vv7-jj25-4gh6 is resolved across your whole dependency graph.
Workarounds
Stop passing untrusted input into the interpreter or shell: call the affected binary with an argument array rather than a composed command string, reject anything outside a strict allowlist of expected values, and run the component under an account that cannot reach beyond the work it legitimately does.

Frequently Asked Questions

### Summary Microsoft Kiota emitted the `x-ms-kiota-info` extension's `clientClassName` or `clientNamespaceName` value **raw**, with no identifier or path sanitization, as **both** the generated client's class/namespace name **and** part of the generated output path. When `kiota generate` is run **without `-c/--class-name`** — the zero-config workflow that `x-ms-kiota-info` is explicitly designed for (the API provider supplies the names in the description so consumers don't have to) — an attacker who controls or tampers with the OpenAPI description could therefore: - **(CWE-22) write the gen

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