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CVE-2026-55637— genieacs-mcp: DNS rebinding reaches local GenieACS MCP Streamable HTTP transport

Quick assessment

Affected
GeiserX genieacs-mcp
Exploitation
Public or AI PoC available; prioritize validation
Recommended action
Check the vendor advisory and references for a fixed version. If immediate upgrade is impossible, restrict exposure and increase monitoring.

genieacs-mcp 是一个基于 Go 语言编写的、用于 GenieACS 的 MCP（Model Context Protocol）服务器。在 0.3.2 版本之前，cmd/server/main.go 中的 Streamable HTTP 传输层在未设置 MCP_AUTH_TOKEN 环境变量时，会在默认监听地址 127.0.0.1:8080 上创建一个无需身份验证的 /mcp 监听端口。同时，在调用 httpSrv.Start(addr) 的分支中，并未对 HTTP 请求的 Host 或 Origin 头

CVSS 8.8 · High

Affected Version Matrix 1

VendorProduct Version RangeStatus
GeiserX genieacs-mcp < 0.3.2 affected
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I. Basic Information for CVE-2026-55637

Vulnerability Information
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Vulnerability Title
genieacs-mcp: DNS rebinding reaches local GenieACS MCP Streamable HTTP transport
Source: CVE Program / CVE List V5
Vulnerability Description
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.
Source: CVE Program / CVE List V5
CVSS Information
CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:P/VC:H/VI:H/VA:N/SC:H/SI:H/SA:N
Source: CVE Program / CVE List V5
Vulnerability Type
源验证错误
Source: CVE Program / CVE List V5

Affected Products

Vendor Product Affected Versions CPE Subscribe
GeiserX genieacs-mcp < 0.3.2 -

II. Public POCs for CVE-2026-55637

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Qwen3.6-35B-A3B · 14127 chars
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III. Intelligence Information for CVE-2026-55637

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Patches & Fixes for CVE-2026-55637 (1)

Other References for CVE-2026-55637 (2)

IV. Related Vulnerabilities

Same weakness: CWE-346

V. Comments for CVE-2026-55637

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