---
id: "CVE-2026-109492"
page: "https://infrastack.ai/live/CVE-2026-109492"
kind: "vulnerability"
aliases: ["CVE-2026-109492"]
title: "Microsoft MCP Gateway: user-controlled key lets authorized users gain higher privileges"
severity: "high"
cvss: 8.8
epss: null
exploited: false
status: "open"
category: "ai-tooling"
products: []
ecosystems: []
tags: ["ai-tooling", "mcp", "mcp-gateway", "microsoft"]
not_affected_if: ["no-mcp-gateway-deployed"]
published_at: "2026-11-10T19:18:17+00:00"
first_seen_at: "2026-11-10T19:24:25+00:00"
updated_at: "2026-11-10T19:35:49+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109492", "first_seen_at": "2026-11-10T19:24:25+00:00"}, {"source": "analyst", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-109492", "first_seen_at": "2026-11-10T19:35:49+00:00", "cites": ["https://nvd.nist.gov/vuln/detail/CVE-2026-109492", "https://github.com/microsoft/mcp-gateway/commit/ea24454"]}]
exploit_sources: []
---

# Microsoft MCP Gateway: user-controlled key lets authorized users gain higher privileges

Link for people: https://infrastack.ai/live/CVE-2026-109492 (this .md is for agents)

Microsoft's open-source MCP Gateway (a reverse proxy routing MCP sessions to servers on Kubernetes) has an authorization flaw: a user-controlled key lets an already-authorized account raise its privileges over the network. Teams running the gateway with more than one user should look at this; teams that don't run it can skip it. The exact exploit path, affected versions and fix are not confirmed by a Microsoft page I could read.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

Microsoft MCP Gateway (github.com/microsoft/mcp-gateway) has no tagged releases, so check whether your deployment was built from a commit before ea24454 (2026-05-22). That commit scopes session keys per user, and may relate to this CVE, but no source confirms it. Affected and fixed versions are unknown. The MSRC entry for CVE-2026-109492 would settle it. Also review who holds mcp.admin or other roles, since the attacker needs a valid account.

## Fix

unknown: no fix version published. Rebuild from current main of microsoft/mcp-gateway; commit ea24454 may be the relevant fix but is unconfirmed for this CVE.

## Timeline

- 2026-11-10T19:24:25+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-109492
- 2026-11-10T19:35:49+00:00 analyst https://nvd.nist.gov/vuln/detail/CVE-2026-109492 — NVD and MSRC pages returned no text; no Microsoft advisory read, so affected/fixed versions are unknown and nothing is verified. microsoft/mcp-gateway has no releases. Commit ea24454 (May 2026, MSRC-112281) scopes session-store keys by user id so a second user can't replay another's mcp-session-id. It may be this CVE's fix, but no source ties it to the CVE id. Linked as 'mentions' only.

## Documents

- [describes] NVD CVE-2026-109492 https://nvd.nist.gov/vuln/detail/CVE-2026-109492
- [mentions] Fix MSRC-112281: SSRF (#79) - microsoft/mcp-gateway https://github.com/microsoft/mcp-gateway/commit/ea24454

## From the sources

Authorization bypass through user-controlled key in Microsoft MCP Gateway allows an authorized attacker to elevate privileges over a network.

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