EXECUTIVE SUMMARY:
A high severity vulnerability CVE-2026-55637 with a CVSS score of 8.8 in genieacs-mcp exposes local Streamable HTTP transport to DNS rebinding attacks, allowing attacker-controlled Host and Origin headers to reach the MCP handler and invoke tools against the configured GenieACS backend without a browser-supplied secret, resulting in unauthorized access to sensitive data and potential business disruption. The vulnerability arises from the server accepting attacker-controlled Host and Origin values without validation, enabling a malicious web page to route browser requests to a victim's loopback MCP listener while preserving the attacker origin. This allows an attacker to bypass authentication and gain unauthorized access to GenieACS tools and data, posing a significant threat to the security of the system.[/subscribe_to_unlock_form]
EXECUTIVE SUMMARY:
A high severity vulnerability CVE-2026-55637 with a CVSS score of 8.8 in genieacs-mcp exposes local Streamable HTTP transport to DNS rebinding attacks, allowing attacker-controlled Host and Origin headers to reach the MCP handler and invoke tools against the configured GenieACS backend without a browser-supplied secret, resulting in unauthorized access to sensitive data and potential business disruption. The vulnerability arises from the server accepting attacker-controlled Host and Origin values without validation, enabling a malicious web page to route browser requests to a victim's loopback MCP listener while preserving the attacker origin. This allows an attacker to bypass authentication and gain unauthorized access to GenieACS tools and data, posing a significant threat to the security of the system.[emaillocker id="1283"]
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The following reports contain further technical details:
https://github.com/advisories/GHSA-cmwv-wf9p-p8wx