CVE-2026-81095

Received Received - Intake

pg-aiguide MCP HTTP Transport Host Allow-List Bypass

Publication date: 2026-08-27

Last updated on: 2026-08-29

Assigner: VulnCheck

Description

pg-aiguide started its MCP HTTP transport without enabling the host allow-list the underlying SDK provides. src/httpServer.ts called the shared httpServerFactory helper and never set the DNS-rebinding-protection option, so the transport accepted a request whatever host it named. A page in a browser could therefore point a name it controlled at the address the server was bound to and drive the locally reachable MCP server through the visitor's browser. The protection was already available in the packaged transport and simply not turned on, so updating the dependency alone would not have closed it. Version 0.5.1 passes the option explicitly.

CVSS Scores

EPSS Scores

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Meta Information

Published

2026-08-27

Last Modified

2026-08-29

Generated

2026-09-16

AI Q&A

2026-08-27

EPSS Evaluated

2026-09-15

NVD

CVE-2026-81095

EUVD

EUVD-2026-67023

Affected Vendors & Products

Vendor	Product	Version / Range
pg-aiguide	mcp_http_transport	0.5.1
timescale	pg-aiguide	to 0.5.1 (exc)
timescale	pg-aiguide	0.5.1

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-346	The product does not properly verify that the source of data or communication is valid.

Attack-Flow Graph

Executive Summary

This vulnerability is a DNS rebinding attack due to a missing host header allow-list in the MCP HTTP transport of pg-aiguide. The SDK provided DNS-rebinding protection but it was not enabled in the implementation. An attacker could exploit this by directing a controlled hostname to the server's address, allowing interaction with the locally reachable MCP server through a victim's browser.

Detection Guidance

Check if pg-aiguide is running a vulnerable version (0.5.0 or earlier) by inspecting the package version in your environment. Verify if DNS rebinding protection is disabled by examining the HTTP server configuration in src/httpServer.ts for the missing dnsRebindingProtection setting.

Impact Analysis

An attacker could exploit this to interact with your locally running MCP server via a browser, potentially accessing sensitive data or executing unauthorized actions. The impact includes high confidentiality and integrity risks as the attacker could read or modify data.

Compliance Impact

This vulnerability could lead to unauthorized access to sensitive data, potentially violating GDPR's data protection principles or HIPAA's security requirements for protected health information. Compliance may be impacted due to increased risk of data breaches.

Mitigation Strategies

Upgrade pg-aiguide to version 0.5.1 or later, which explicitly enables DNS rebinding protection. Ensure the dnsRebindingProtection option is set in the HTTP server configuration, especially for local development environments.

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