CVE-2026-116685: Model Context Protocol Python SDK credential leakage via redirects

# CVE-2026-116685: Model Context Protocol Python SDK credential leakage via redirects

https://gcdradar.vercel.app/incidents/cve-2026-116685-model-context-protocol-python-sdk-credential · AIR-2026-1586 · closed 2026-10-27

- Lane: Patch now
- Severity: 2 (Disclosed vulnerability): CVE advisory with patches available and no exploitation reported.
- Fix status: Patched
- First reported: 2026-10-27
- AI role: Attack on AI
- Products: Model Context Protocol Python SDK
- CVE ids: CVE-2026-116685
- CVSS: 5.9

## Summary

Certain client paths in the Model Context Protocol Python SDK improperly follow cross-origin redirects, forwarding custom credential headers and request bodies. Attackers able to manipulate redirect destinations can capture sensitive authentication material.

## What to do

Update to version 1.30.0 or 2.2.0.

## Affected and fixed versions

- Affected: 1.8.0 to 1.29.x
- Affected: 2.0.0 to 2.1.x
- Fixed in: 1.30.0
- Fixed in: 2.2.0

## Latest updates

- 2026-10-27: GitHub advisory published (https://github.com/advisories/GHSA-5h93-6whr-6q8j)
- 2026-10-27: CVE-2026-116685: The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. (https://nvd.nist.gov/vuln/detail/CVE-2026-116685)

## Sources

- 2026-10-27 NVD: CVE-2026-116685: The Model Context Protocol Python SDK is the official Python SDK for Model Context Protocol servers and clients. https://nvd.nist.gov/vuln/detail/CVE-2026-116685
- 2026-10-27 GitHub Advisory Database: CVE-2026-116685: Model Context Protocol Python SDK: HTTP client transports followed cross-origin redirects carrying custom headers and bodies https://github.com/advisories/GHSA-5h93-6whr-6q8j

Verify against the vendor's advisory before changing production. Data CC BY-SA 4.0, https://gcdradar.vercel.app.