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CVE-2026-116685

CVE-2026-116685 · Model Context Protocol Python SDK: HTTP client transports followed cross-origin redirects carrying custom headers and bodies

This page contains facts from public vulnerability sources. Check the original advisory before updating.

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.

CVSS 5.9 · Medium · EPSS 0.4% · Fix available

Published
Updated

Stack: python

Affected products and versions

  • python-sdk

    Versions
    • >= 1.8.0, < 1.30.0: Affected
    • >= 2.0.0, < 2.2.0: Affected

    No fix published

  • mcp PyPI

    Versions
    • 2.0.0
    • 2.0.1
    • 2.1.0
    • 2.1.1
    Affected ranges
    • ECOSYSTEM: ≥ 2.0.0, < 2.2.0

    Update to 2.2.0

  • mcp PyPI

    Versions
    • 1.10.0
    • 1.10.1
    • 1.11.0
    • 1.12.0
    • 1.12.1
    • 1.12.2
    • 1.12.3
    • 1.12.4
    • 1.13.0
    • 1.13.1
    • 1.14.0
    • 1.14.1
    • 1.15.0
    • 1.16.0
    • 1.17.0
    • 1.18.0
    • 1.19.0
    • 1.20.0
    • 1.21.0
    • 1.21.1
    • 1.21.2
    • 1.22.0
    • 1.23.0
    • 1.23.1
    • 1.23.2
    • 1.23.3
    • 1.24.0
    • 1.25.0
    • 1.26.0
    • 1.27.0
    • 1.27.1
    • 1.27.2
    • 1.28.0
    • 1.28.1
    • 1.29.0
    • 1.29.1
    • 1.8.0
    • 1.8.1
    • 1.9.0
    • 1.9.1
    • 1.9.2
    • 1.9.3
    • 1.9.4
    Affected ranges
    • ECOSYSTEM: ≥ 1.8.0, < 1.30.0

    Update to 1.30.0

Original sources

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