---
id: CVE-2026-55637
title: genieacs-mcp is an MCP server for GenieACS written in Go
summary: >-
  genieacs-mcp is an MCP server for GenieACS written in Go. Prior to 0.3.2, the
  Streamable HTTP transport in cmd/server/main.go creates an unauthenticated
  /mcp listener on the default MCP_LISTEN_ADDR value 127.0.0.1:8080 when
  MCP_AUTH_TOKE…
severity: high
cwe:
  - CWE-346
vendor: geiserx
product: github.com/geiserx/genieacs-mcp
affected:
  - github.com/geiserx/genieacs-mcp <= 0.3.1
patched:
  - github.com/geiserx/genieacs-mcp 0.3.2
published: '2026-08-25'
updated: '2026-09-09'
sourceUpdated: '2026-09-09T21:07:31.353'
source: NVD
sourceUrl: 'https://nvd.nist.gov/vuln/detail/CVE-2026-55637'
references:
  - url: >-
      https://github.com/GeiserX/genieacs-mcp/commit/577306d78190622eee97e362b042a69499ef373f
    label: security-advisories@github.com
  - url: 'https://github.com/GeiserX/genieacs-mcp/pull/26'
    label: security-advisories@github.com
  - url: 'https://github.com/GeiserX/genieacs-mcp/releases/tag/v0.3.2'
    label: security-advisories@github.com
  - url: >-
      https://github.com/GeiserX/genieacs-mcp/security/advisories/GHSA-cmwv-wf9p-p8wx
    label: security-advisories@github.com
  - url: >-
      https://github.com/GeiserX/genieacs-mcp/security/advisories/GHSA-cmwv-wf9p-p8wx
    label: 134c704f-9b21-4f2e-91b3-4a467353bcc0
  - url: 'https://github.com/advisories/GHSA-cmwv-wf9p-p8wx'
tags:
  - nvd
  - ghsa
  - go
epss: 0.00264
epssPercentile: 0.16307
aliases:
  - GHSA-cmwv-wf9p-p8wx
ecosystem: go
ingestedAt: '2026-08-25T18:30:21.350Z'
---

## Overview

genieacs-mcp is an MCP server for GenieACS written in Go. Prior to 0.3.2, the Streamable HTTP transport in cmd/server/main.go creates an unauthenticated /mcp listener on the default MCP_LISTEN_ADDR value 127.0.0.1:8080 when MCP_AUTH_TOKEN is unset and the httpSrv.Start(addr) branch does not validate the Host or Origin headers. A malicious website can use DNS rebinding to send browser requests with attacker-controlled Host and Origin values to the loopback listener, initialize an MCP session, list tools, and invoke operations against the GenieACS NBI configured by ACS_URL. Successful exploitation can expose or modify CPE management state, including device reboots, firmware tasks, TR-069 parameter changes, presets, provisions, tags, connection requests, and task operations. The npm wrapper is not affected because it forces TRANSPORT=stdio and does not expose an HTTP listener. This issue is fixed in version 0.3.2.

## Remediation

Refer to the linked advisories for vendor-supplied fixes and affected version ranges.

## Package advisory (CVE-2026-55637)

Affected packages:

- `github.com/geiserx/genieacs-mcp <= 0.3.1`

Patched in:

- `github.com/geiserx/genieacs-mcp 0.3.2`

Source: https://github.com/advisories/GHSA-cmwv-wf9p-p8wx