Vulnerability 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.
CVSS Score
MEDIUM
Related Weaknesses (CWE)
References
- https://github.com/modelcontextprotocol/python-sdk/commit/2106335745563b2321b8c7
- https://github.com/modelcontextprotocol/python-sdk/commit/c6762e821c527925f0b617
- https://github.com/modelcontextprotocol/python-sdk/pull/3397
- https://github.com/modelcontextprotocol/python-sdk/pull/3448
- https://github.com/modelcontextprotocol/python-sdk/releases/tag/v1.30.0
- https://github.com/modelcontextprotocol/python-sdk/releases/tag/v2.2.0
- https://github.com/modelcontextprotocol/python-sdk/security/advisories/GHSA-5h93
FAQ
What is CVE-2026-116685?
CVE-2026-116685 is a vulnerability with a CVSS score of 5.9 (MEDIUM). 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_c...
How severe is CVE-2026-116685?
CVE-2026-116685 has been rated MEDIUM with a CVSS base score of 5.9/10. Review the CVSS metrics above for detailed severity breakdown.
Is there a patch for CVE-2026-116685?
Check the references section above for vendor advisories and patch information. Review vendor security bulletins for remediation guidance.