CVE-2026-55637
HIGHDescription
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.
How to fix
No published remediation has been found for this vulnerability's affected products yet.
Mitigation guidance may be in the linked vendor advisories in the References section below.
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CVSS v4 Vector
Exploitability
Impact
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/E:X/CR:X/IR:X/AR:X/MAV:X/MAC:X/MAT:X/MPR:X/MUI:X/MVC:X/MVI:X/MVA:X/MSC:X/MSI:X/MSA:X/S:X/AU:X/R:X/V:X/RE:X/U:X
Exploit Intelligence
Low risk: more likely to be exploited than 10% of all known CVEs.
References
Related Vulnerabilities
Other CWE-346 vulnerabilities, ordered by exploit likelihood. View all
| CVE | Severity | CVSS | EPSS | Exploited | Fix |
|---|---|---|---|---|---|
| CVE-2025-34291 | High | 8.8 | 84% | KEV | - |
| CVE-2009-1185 | High | 7.2 | 82% | - | Fix |
| CVE-2015-4495 | High | 8.8 | 71% | KEV | Fix |
| CVE-2020-16952 | High | 8.6 | 71% | - | - |
| CVE-2023-29711 | Critical | 9.8 | 70% | - | - |
| CVE-2024-23898 | High | 8.8 | 67% | - | Fix |
Common questions
How do I fix CVE-2026-55637?
No published fix for CVE-2026-55637 has been found yet. Check the linked vendor advisories for guidance as it becomes available.
Is CVE-2026-55637 being actively exploited?
Not that we know of. CVE-2026-55637 is not in the CISA Known Exploited Vulnerabilities catalog. Its EPSS score of 0.21% is the estimated probability that it will be exploited in the next 30 days. That is higher than 10% of all scored CVEs.
How severe is CVE-2026-55637?
CVE-2026-55637 has a CVSS v4 base score of 8.8, rated high. CVSS rates the technical impact if the vulnerability is exploited, not how likely that is, so weigh it alongside the exploit-prediction score when you decide what to patch first.
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This product uses NVD data but is not endorsed or certified by the NVD. EPSS scores courtesy of FIRST.org (https://www.first.org/epss). Source: CISA KEV Catalog. Data as of 2026-08-25.