Kotlin Sdk
Monthly
Memory exhaustion in the Model Context Protocol (MCP) Kotlin SDK through version 0.15.0 allows unauthenticated remote clients to drive a server into denial of service by sending WebSocket frames whose headers declare payloads approaching 2 GiB, forcing the server to attempt huge heap allocations before any frame body is received. The flaw lives in the SDK's Application.mcpWebSocket extension, which installs Ktor WebSockets without a maxFrameSize limit, and because that unprotected configuration is the installed default, no special toggle or misconfiguration is required. Impact is availability-only (no confidentiality or integrity loss), the practical limiting factor is network reachability to an exposed WebSocket endpoint running an affected version, and no public exploit code or active exploitation has been identified at time of analysis.
Memory exhaustion in the Model Context Protocol (MCP) Kotlin SDK through version 0.15.0 allows unauthenticated remote clients to drive a server into denial of service by sending WebSocket frames whose headers declare payloads approaching 2 GiB, forcing the server to attempt huge heap allocations before any frame body is received. The flaw lives in the SDK's Application.mcpWebSocket extension, which installs Ktor WebSockets without a maxFrameSize limit, and because that unprotected configuration is the installed default, no special toggle or misconfiguration is required. Impact is availability-only (no confidentiality or integrity loss), the practical limiting factor is network reachability to an exposed WebSocket endpoint running an affected version, and no public exploit code or active exploitation has been identified at time of analysis.