CVE-2026-111770 Model Context Protocol TypeScript SDK: Shared transport or server instances delivered one HTTP client's messages to another

The Model Context Protocol TypeScript SDK provides TypeScript client and server implementations of the Model Context Protocol. From 2.0.0 until 2.3.0 in @modelcontextprotocol/server, applications that shared one stateless HTTP transport or one McpServer or Server instance among multiple clients...

MCP TypeScript server SDK: Shared transport or server instances delivered one HTTP client's messages to another

Summary In affected versions, an MCP server reached over HTTP could deliver one client's responses and notifications to another client. This happened when clients shared one stateless transport, or one McpServer or Server instance. Messages were matched to a connection by JSON-RPC id alone. SDK...

GHSA-JM63-CQ47-J5JP MCP TypeScript server SDK: Shared transport or server instances delivered one HTTP client's messages to another

Summary In affected versions, an MCP server reached over HTTP could deliver one client's responses and notifications to another client. This happened when clients shared one stateless transport, or one McpServer or Server instance. Messages were matched to a connection by JSON-RPC id alone. SDK...

MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation

Summary In affected versions, servers put no limit on how many array elements and object keys they validated in one request. One HTTP request within the default 4 MiB size limit could exhaust the server's memory, and the process aborted with JavaScript heap out of memory. No credentials are neede...

GHSA-46JR-4WX8-V453 MCP TypeScript SDK: One HTTP request within the default size limit could exhaust server memory during validation

Summary In affected versions, servers put no limit on how many array elements and object keys they validated in one request. One HTTP request within the default 4 MiB size limit could exhaust the server's memory, and the process aborted with JavaScript heap out of memory. No credentials are neede...

PT-2026-120341

Name of the Vulnerable Software and Affected Versions @modelcontextprotocol/sdk versions 1.3.0 through 1.31.0 @modelcontextprotocol/server versions 2.0.0 through 2.2.0 Description HTTP servers do not enforce a limit on the number of array elements and object keys validated in a single request. An...

PT-2026-120151

Name of the Vulnerable Software and Affected Versions @modelcontextprotocol/server versions 2.0.0 through 2.2.0 Description An MCP server accessed over HTTP may deliver responses and notifications from one client to another. This occurs when clients share a single stateless transport, McpServer...

PT-2026-120294

Summary In affected versions, servers put no limit on how many array elements and object keys they validated in one request. One HTTP request within the default 4 MiB size limit could exhaust the server's memory, and the process aborted with JavaScript heap out of memory. No credentials are neede...

SUSE CVE-2026-59951

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamablehttpapp, and StreamableHTTPSessionManager, retain session entries without an id...

MCP Python SDK: Unbounded Session Accumulation in StreamableHTTP Transport Enables Resource Exhaustion

Summary In affected versions, a Streamable HTTP server in stateful mode the default never reclaimed session state: - sessions did not expire; - a client DELETE ended the session but left its entry registered; - a session whose first request was refused stayed registered with a running task. Each...

GHSA-84M7-P3X7-PCFV MCP Python SDK: Unbounded Session Accumulation in StreamableHTTP Transport Enables Resource Exhaustion

Summary In affected versions, a Streamable HTTP server in stateful mode the default never reclaimed session state: - sessions did not expire; - a client DELETE ended the session but left its entry registered; - a session whose first request was refused stayed registered with a running task. Each...

EUVD-2026-101452

MCP Python SDK: Unbounded Session Accumulation in StreamableHTTP Transport Enables Resource Exhaustion...

CVE-2026-59951

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamablehttpapp, and StreamableHTTPSessionManager, retain session entries without an id...

CVE-2026-59951 MCP Python SDK: Unbounded Session Accumulation in StreamableHTTP Transport Enables Resource Exhaustion

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamablehttpapp, and StreamableHTTPSessionManager, retain session entries without an id...

CVE-2026-59951 MCP Python SDK: Unbounded Session Accumulation in StreamableHTTP Transport Enables Resource Exhaustion

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamablehttpapp, and StreamableHTTPSessionManager, retain session entries without an id...

CVE-2026-59951 MCP Python SDK: Unbounded Session Accumulation in StreamableHTTP Transport Enables Resource Exhaustion

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamablehttpapp, and StreamableHTTPSessionManager, retain session entries without an id...

CVE-2026-59951

The MCP Python SDK (PyPI: mcp) versions 1.8.0 through 1.30.0 and 2.2.0 are vulnerable to unbounded session accumulation within the StreamableHTTP transport . Specifically, stateful servers—including FastMCP , MCPServer , Server.streamable_http_app() , and StreamableHTTPSessionManager —fail to exp...

CVE-2026-59951

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamablehttpapp, and StreamableHTTPSessionManager, retain session entries without an id...

CVE-2026-59951: Uncontrolled Resource Consumption

The MCP Python SDK, called mcp on PyPI, is a Python implementation of the Model Context Protocol MCP. From 1.8.0 until 1.30.0 and 2.2.0, stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamablehttpapp, and StreamableHTTPSessionManager, retain session entries without an id...

PT-2026-114229

Name of the Vulnerable Software and Affected Versions mcp versions 1.8.0 through 1.29.9 mcp versions 2.0.0 through 2.1.9 Description Stateful Streamable HTTP servers, including FastMCP, MCPServer, Server.streamable http app, and StreamableHTTPSessionManager, retain session entries without an idle...