---
id: CVE-2026-59867
aliases:
  - GHSA-rg4h-fpcp-2qm8
title: >-
  Microsoft Kiota: Generation-time SSRF + remote/local file inclusion via
  unrestricted $ref
summary: >-
  Microsoft Kiota: Generation-time SSRF + remote/local file inclusion via
  unrestricted $ref
severity: high
cvss: 7.1
cwe:
  - CWE-22
  - CWE-829
  - CWE-918
vendor: Microsoft
product: Microsoft.OpenApi.Kiota
ecosystem: nuget
affected:
  - Microsoft.OpenApi.Kiota < 1.32.5
  - Microsoft.OpenApi.Kiota.Builder < 1.32.5
patched:
  - Microsoft.OpenApi.Kiota 1.32.5
  - Microsoft.OpenApi.Kiota.Builder 1.32.5
published: '2026-07-24'
updated: '2026-07-24'
source: GHSA
sourceUrl: 'https://github.com/advisories/GHSA-rg4h-fpcp-2qm8'
references:
  - url: 'https://github.com/microsoft/kiota/security/advisories/GHSA-rg4h-fpcp-2qm8'
  - url: 'https://nvd.nist.gov/vuln/detail/CVE-2026-59867'
  - url: 'https://github.com/microsoft/kiota/pull/7888'
  - url: >-
      https://github.com/microsoft/kiota/commit/cccd798027f0a20db796b3df6c64f9897a39d7b1
  - url: 'https://github.com/microsoft/kiota/releases/tag/v1.32.5'
  - url: 'https://github.com/advisories/GHSA-rg4h-fpcp-2qm8'
tags:
  - ghsa
  - nuget
epss: 0.02393
epssPercentile: 0.83275
ingestedAt: '2026-07-24T16:33:09.707Z'
---

## Overview

## Summary

Microsoft Kiota resolved OpenAPI `$ref`s by fetching remote `http(s)` URLs and reading local files
(including absolute / out-of-tree paths), inlining the referenced schema into the generated client.
Running `kiota generate` on a spec whose `$ref` pointed at an attacker/internal URL or an arbitrary
local file yielded SSRF, remote file inclusion, and local file inclusion. Verified on **1.32.3 / 1.32.4**.

### Details

- `$ref: http://attacker/internal-evil.json#/...` → build host fetches the URL (SSRF) and inlines the
  remote schema (RFI); confirmed property `REMOTE_KIOTA_PROP` in the generated client.
- `$ref: /abs/path.json#/...` or `../../secret.json#/...` → Kiota reads the out-of-tree local file and
  inlines its schema (LFI); confirmed `Leaked` schema in the generated client. Resolution is transitive
  across nesting levels.

Kiota **escapes** its output sinks (comments/strings/identifiers), so attacker-controlled remote/local
content cannot break out into code — no RCE. The chain stops at SSRF + RFI + LFI.

### Impact

Build-time SSRF (CWE-918) from the developer or CI host, disclosure of arbitrary local files (CWE-22), and
inclusion of untrusted remote content (CWE-829), from running the generator on an attacker-controlled or
attacker-influenced OpenAPI description. No code execution. Notable because Kiota is otherwise the hardened
generator (it resists the code-injection class).

The relevant threat is not "change the generated output" (an attacker who fully controls the description can
already do that) but the **side effects on the build host**: outbound requests from inside the CI network
(cloud metadata, internal-only services) and reads of local files the attacker never possessed, whose contents
are then inlined into the generated — and typically committed/published — client. It also bypasses controls
that review the description document but not externally-referenced content.

### Patches

Fixed in **1.32.5** (https://github.com/microsoft/kiota/pull/7888). External reference resolution is now
**default-deny**: a new `AllowedExternalOriginsStreamLoader` refuses to load any external `$ref` — remote
`http(s)` URLs and local file paths alike — unless its origin/path is explicitly allow-listed. A new
`--allowed-external-origins` parameter (added to the commands that load OpenAPI descriptions) opts specific
origins back in, accepting `*`, full URIs, URI patterns, full paths, relative paths, or path patterns
(wildcards supported). With no allow-list entries, external references are not loaded at all.

### Remediation

Upgrade to Kiota **1.32.5** or later. External references now require explicit opt-in via
`--allowed-external-origins`; add only trusted origins/paths.

## Affected packages

- `Microsoft.OpenApi.Kiota < 1.32.5`
- `Microsoft.OpenApi.Kiota.Builder < 1.32.5`

## Remediation

Upgrade to a patched release:

- `Microsoft.OpenApi.Kiota 1.32.5`
- `Microsoft.OpenApi.Kiota.Builder 1.32.5`