AIKIDO-2026-11083
mcp is vulnerable to Authorization Bypass
71
High Risk
This Affects:
mcpTL;DR
On authenticated MCP servers using stateful SSE or Streamable HTTP transports, session IDs were not bound to the credential that created each session, so a different authenticated principal could reuse a leaked session ID and interact with another user's session. When experimental tasks are enabled on stateful servers, default task handlers also did not scope task IDs to the creating session, allowing cross-session task get, result, cancel, and list operations. The patch records the creating principal on transport sessions and embeds an opaque per-session marker in generated task IDs so default handlers reject out-of-scope access.
Who does this affect?
You are affected if you are using a version that falls within the vulnerable range.
Background info
mcp is vulnerable to Authorization Bypass in versions 1.7.0 - 1.27.1.
How to fix this
Upgrade the mcp library to the patch version.
Are You Affected?
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SOC 2Compliant
ISO 27001Compliant