---
id: "CVE-2026-65957"
page: "https://infrastack.ai/live/CVE-2026-65957"
kind: "vulnerability"
aliases: ["CVE-2026-65957"]
title: "Helio MCP proxy: CORS check lets attacker websites reach dashboard"
severity: "medium"
cvss: 6.9
epss: null
exploited: false
status: "open"
category: "ai-tooling"
products: []
ecosystems: []
tags: ["ai-agents", "ai-tooling", "helio", "local-dev", "mcp"]
not_affected_if: ["dashboard-disabled", "version-0.8.0-or-later"]
published_at: "2026-11-11T21:16:46+00:00"
first_seen_at: "2026-11-11T21:29:09+00:00"
updated_at: "2026-11-11T21:30:51+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-65957", "first_seen_at": "2026-11-11T21:29:09+00:00"}]
exploit_sources: []
---

# Helio MCP proxy: CORS check lets attacker websites reach dashboard

Link for people: https://infrastack.ai/live/CVE-2026-65957 (this .md is for agents)

Helio is an MCP proxy that sits between AI agents and their tools. Before version 0.8.0, its dashboard accepted cross-origin requests from public domains whose names start with private-network prefixes, so a malicious web page can read responses from the local dashboard.

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

## How to check

- Check the installed Helio version; versions below `0.8.0` are affected.
- Check whether the dashboard sideband is reachable on its default `127.0.0.1:3100`, which the sources describe as the default bind.

## Fix

- Helio: move to `0.8.0` or later.

## Timeline

- 2026-11-11T21:29:09+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-65957

## Documents

- [advisory] Vendor advisory: github.com https://github.com/gethelio/helio/security/advisories/GHSA-2c3r-q7gv-hp2m
- [fix] Patch: github.com https://github.com/gethelio/helio/commit/4ca8329c38b0edbc5e4d782a4e3b0cfc5cd7782e
- [fix] Release notes: github.com https://github.com/gethelio/helio/releases/tag/v0.8.0

## From the sources

Helio is an MCP proxy that sits between AI agents and the tools they use. Prior to version 0.8.0, the dashboard sideband (default 127.0.0.1:3100) validated CORS request origins by matching the hostname against a private-network string prefix (10., 172.16.–172.31., 192.168.) rather than validating an IP address. A public DNS name such as 192.168.attacker.com, 10.evil.io, or 172.16.pwn.example also satisfies that prefix, so the proxy echoed the attacker origin in Access-Control-Allow-Origin. This issue has been patched in version 0.8.0.

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