CVE-2026-81100
Received Received - Intake

Tiger-GH-MCP-Server Unrestricted Host Access Vulnerability

Publication date: 2026-08-27

Last updated on: 2026-08-27

Assigner: VulnCheck

Description
tiger-gh-mcp-server 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, making the locally reachable GitHub MCP endpoint drivable from a page in a visitor's browser that pointed a name it controlled at the bound address. The fix passes the option explicitly alongside a dependency update; the update alone would not have closed it. The repository has published no release that brackets the fix, so the affected boundary is the commit preceding it.

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Meta Information

Published
2026-08-27
Last Modified
2026-08-27
Generated
2026-08-27
AI Q&A
2026-08-27
EPSS Evaluated
N/A
NVD
CVE-2026-81100
EUVD
EUVD-2026-67028

Affected Vendors & Products

Showing 1 associated CPE
Vendor Product Version / Range
timescale tiger-gh-mcp-server to e559b57b57cf61277525ec96bbf1edcf01b16a21 (exc)

Helpful Resources

Exploitability

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

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Executive Summary

CVE-2026-81100 is a DNS rebinding vulnerability in the tiger-gh-mcp-server. The server's HTTP transport did not enable the host allow-list provided by the underlying SDK, allowing requests from any host. This exposed the locally reachable GitHub MCP endpoint to potential exploitation from a malicious webpage controlled by an attacker.

Detection Guidance

Check if the tiger-gh-mcp-server HTTP transport is running without DNS rebinding protection. Verify the server's configuration to ensure Host header allow-list validation is enabled in development environments. Inspect network traffic for requests originating from unexpected hosts.

Impact Analysis

An attacker could use a victim's browser to send requests to the unauthenticated local server by pointing a controlled domain at the server's address. This could allow the attacker to interact with the GitHub MCP endpoint, potentially accessing or manipulating data.

Mitigation Strategies

Update to the latest commit that includes DNS rebinding protection. Ensure Host header allow-list validation is enabled in development environments, restricting access to localhost, 127.0.0.1, and [::1]. Disable the server if not in use.

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