{"id":"CVE-2026-55637","summary":"genieacs-mcp: DNS rebinding reaches local GenieACS MCP Streamable HTTP transport","details":"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.","aliases":["GHSA-cmwv-wf9p-p8wx","GO-2026-6295"],"modified":"2026-09-11T03:30:41.935008714Z","published":"2026-08-25T18:03:34.701Z","related":["openSUSE-SU-2026:21761-1"],"database_specific":{"cwe_ids":["CWE-346"],"osv_generated_from":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55637.json","cna_assigner":"GitHub_M"},"references":[{"type":"WEB","url":"https://github.com/GeiserX/genieacs-mcp/releases/tag/v0.3.2"},{"type":"ADVISORY","url":"https://github.com/CVEProject/cvelistV5/tree/main/cves/2026/55xxx/CVE-2026-55637.json"},{"type":"ADVISORY","url":"https://github.com/GeiserX/genieacs-mcp/security/advisories/GHSA-cmwv-wf9p-p8wx"},{"type":"ADVISORY","url":"https://nvd.nist.gov/vuln/detail/CVE-2026-55637"},{"type":"FIX","url":"https://github.com/GeiserX/genieacs-mcp/commit/577306d78190622eee97e362b042a69499ef373f"},{"type":"FIX","url":"https://github.com/GeiserX/genieacs-mcp/pull/26"}],"affected":[{"ranges":[{"type":"GIT","repo":"https://github.com/geiserx/genieacs-mcp","events":[{"introduced":"0"},{"fixed":"577306d78190622eee97e362b042a69499ef373f"},{"fixed":"6455588e54cbbc32742852c652c35def6fa605c6"}],"database_specific":{"source":["AFFECTED_FIELD","REFERENCES"],"extracted_events":[{"introduced":"0"},{"fixed":"0.3.2"}]}}],"versions":["v0.3.1","v0.3.0","v0.2.0","v0.1.0","v0.0.11","v0.0.10","v0.0.9","v0.0.8","v0.0.7","v0.0.6","v0.0.5","v0.0.4","v0.0.3","v0.0.2","v0.0.1"],"database_specific":{"source":"https://storage.googleapis.com/cve-osv-conversion/osv-output/CVE-2026-55637.json"}}],"schema_version":"1.9.0","severity":[{"type":"CVSS_V4","score":"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"}]}