CVE-2026-55637

Published Aug 25, 2026 Modified Aug 25, 2026 CWE-346

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.

Is your site exposed to CVE-2026-55637?

Run a free security scan — no signup, results in seconds.

EPSS — Exploit Prediction

0.0021
Probability of exploitation
0.10%
Percentile rank

EPSS estimates the probability that this vulnerability will be exploited in the wild within the next 30 days. A higher score means more likely to be exploited.

Weakness Type (CWE)

CWE-346 CWE-346

References

Frequently Asked Questions

What is CVE-2026-55637? +
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 do I check if I'm vulnerable to CVE-2026-55637? +
You can use Secably's free Website Scanner to check your website for known vulnerabilities. For infrastructure scanning, use the Port Scanner to identify exposed services that may be affected. Check the vendor advisories linked above for specific patch and version information.

Related Vulnerabilities

CVE-2026-22077

OPPO Wallet APP contains a trusted domain validation flaw that allows attackers to bypass protected interface access restrictions, which may …
CVE-2026-45173

Idira Identity Browser Extension (Chrome, Firefox, and Edge builds) versions prior to 26.8.1 exhibit an origin validation flaw within its …
CVE-2025-3651

Improper Verification of Source of a Communication Channel in Work Desktop for Mac versions 10.8.1.46 and earlier allows attackers to …
CVE-2025-3462

"This issue is limited to motherboards and does not affect laptops, desktop computers, or other endpoints." An insufficient validation in …
CVE-2025-53399

In Sipwise rtpengine before 13.4.1.1, an origin-validation error in the endpoint-learning logic of the media-relay core allows remote attackers to …
CVE-2025-10193

DNS rebinding vulnerability in Neo4j Cypher MCP server allows malicious websites to bypass Same-Origin Policy protections and execute unauthorised tool …

Don't wait for an exploit

Scan your website for vulnerabilities like CVE-2026-55637 — free, no signup required.