MCP Attacks

Test NameAPI IDDescriptionDetectable Vulnerabilities
AESI: ANSI Escape Sequence InjectionaesiChecks whether MCP tools, resources, or prompt templates can fetch external content and return ANSI-concealed instructions that are hidden from terminal users but still visible to downstream modelsAESI: ANSI Escape Sequence Injection
Stored AESI: ANSI Escape Sequence Injectionstored_aesiChecks whether MCP integrations can persist externally hosted ANSI-concealed instructions and expose them later to downstream modelsStored AESI: ANSI Escape Sequence Injection
MCP Predictable Session IDmcp_predictable_session_idChecks whether an MCP server generates Mcp-Session-Id values with enough randomness to prevent an attacker from guessing a valid session and hijacking another client's MCP sessionMCP Predictable Session ID
MCP Session ID as Authenticationmcp_session_as_authChecks whether the MCP server re-verifies application-level authentication on every request or relies on the session ID alone, allowing session-replay attacksMCP Session ID as Authentication
MCP Lack of Session Invalidationmcp_session_not_invalidatedChecks whether the MCP server actually removes sessions when it confirms termination via HTTP DELETE, preventing post-logout session reuseMCP Lack of Session Invalidation

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