AI agent incident

An OAuth flaw in the MCP Python SDK could enable account takeover

Reported · 1 source

What happened

Cycode reported an OAuth flaw in the MCP Python SDK that could enable account takeover on MCP servers built with it.

Why it matters

An SDK flaw is inherited by every server built on it, whether or not that team ever read the OAuth code. Taking over an agent identity means taking over everything it was trusted with, so check the SDK version your servers pin.

Sources

  1. Cycode MCP Python SDK OAuth flaw enabled account takeover

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Background reading

What is an MCP gateway? An explainer on the problem behind this incident.

In the tools directory

This page lists this record as a related incident, next to the products in the category and questions to ask their vendors.

Cite or correct this record

“An OAuth flaw in the MCP Python SDK could enable account takeover.” The Permission Layer AI Agent Incident Database, https://thepermissionlayer.com/incidents/mcp-python-sdk-oauth-account-takeover/. Database updated October 22, 2026.

Every record traces to the dated sources above. If something here is wrong or missing, email [email protected] and it gets fixed. See this record in the full list.

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