CVE-2026-55637genieacs-mcp: DNS rebinding reaches local GenieACS MCP Streamable HTTP transport
Updated under an hour ago ()
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It affects GeiserX genieacs-mcp. Add what you run to find out whether that includes you.
No exploitation reported and no EPSS estimate yet.
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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.
- CVSS
- 8.8 HIGH (v4.0, CNA)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
- Weakness (CWE)
- CWE-346
- Known exploited
- Not in CISA's KEV catalog
- EPSS (exploitation in the next 30 days)
- Not loaded for this CVE
- Assigned by
- GitHub_M
- NVD analysis
- Deferred
- Record last updated
- Aug 25, 2026
- First seen by InfoSec Signals
- Oct 9, 2026
Affected products
GeiserX genieacs-mcp geiserx:genieacs_mcp (from the name) | before 0.3.2 | CNA record |
References
- https://github.com/GeiserX/genieacs-mcp/security/advisories/GHSA-cmwv-wf9p-p8wxx-refsource-confirm
- https://github.com/GeiserX/genieacs-mcp/pull/26x-refsource-misc
- https://github.com/GeiserX/genieacs-mcp/commit/577306d78190622eee97e362b042a69499ef373fx-refsource-misc
- https://github.com/GeiserX/genieacs-mcp/releases/tag/v0.3.2x-refsource-misc
The CVE record on cve.org NVD's entry
The CVE record is authoritative. Products marked “from the name” were identified from the CNA's free-text names, not a CPE, and are matched less certainly. This product uses the NVD API but is not endorsed or certified by the NVD.