CVE-2026-116685
Received Received - Intake

Open Redirect in Model Context Protocol Python SDK

Publication date: 2026-10-27

Last updated on: 2026-10-27

Assigner: GitHub, Inc.

Description
The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. From 1.8.0 until 1.30.0 and 2.2.0, streamable_http_client, streamablehttp_client, sse_client, ClientSessionGroup, OAuth, and create_mcp_http_client client paths enable follow_redirects and follow redirects to a different origin, forwarding caller-supplied custom credential headers and, for 307 or 308 responses, the request body. An attacker who can influence a trusted endpoint's redirect destination can receive that material. This issue is fixed in versions 1.30.0 and 2.2.0.

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Meta Information

Published
2026-10-27
Last Modified
2026-10-27
Generated
2026-10-27
AI Q&A
2026-10-27
EPSS Evaluated
N/A
NVD
CVE-2026-116685
EUVD
EUVD-2026-111367

Affected Vendors & Products

Showing 2 associated CPEs
Vendor Product Version / Range
modelcontextprotocol python-sdk >= 1.8.0, < 1.30.0
modelcontextprotocol python-sdk >= 2.0.0, < 2.2.0

Helpful Resources

Exploitability

CWE
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KEV
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CWE ID Description
CWE-200 The product exposes sensitive information to an actor that is not explicitly authorized to have access to that information.

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Executive Summary

The vulnerability in the Model Context Protocol Python SDK allows client paths like streamable_http_client and OAuth to follow redirects to different origins. This can forward custom credential headers and request bodies to attacker-controlled endpoints if a trusted URL is redirected maliciously. The issue affects versions between 1.8.0 and 1.30.0, and up to 2.2.0.

Impact Analysis

An attacker could exploit this to steal sensitive credentials or data by tricking users into visiting a compromised trusted endpoint that redirects to a malicious server. This could lead to unauthorized access to accounts or sensitive information.

Compliance Impact

This vulnerability could lead to unauthorized data exposure, violating GDPR's data protection principles or HIPAA's safeguards for protected health information. Organizations using affected versions may face compliance violations and legal consequences.

Mitigation Strategies

Update the Model Context Protocol Python SDK to version 1.30.0 or 2.2.0 or later to address the vulnerability.

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