# CVE-2026-55637

## Summary

- **CVE ID:** CVE-2026-55637
- **Severity:** HIGH
- **CVSS Score:** 8.8 (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)
- **CWE:** CWE-346
- **Published:** Aug 25, 2026
- **Last Modified:** Aug 25, 2026

## 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.

## Affected Products

- GeiserX — genieacs-mcp (< 0.3.2)

## References

- [CNA](https://github.com/GeiserX/genieacs-mcp/security/advisories/GHSA-cmwv-wf9p-p8wx)
- [CNA](https://github.com/GeiserX/genieacs-mcp/pull/26)
- [CNA](https://github.com/GeiserX/genieacs-mcp/commit/577306d78190622eee97e362b042a69499ef373f)
- [CNA](https://github.com/GeiserX/genieacs-mcp/releases/tag/v0.3.2)

## Exploitation Prediction (EPSS)

- **EPSS Score:** 0.21%
- **EPSS Percentile:** 10.5

---
_Exported from OnDuty AI Vulnerability Intelligence on 2026-09-12._