CVE-2026-120216: fastify is a web framework for Node.js. In versions 5.8.0 through 5.12.7, when the server is configured with a nonzero handlerTimeout and a route returns a stre

fastify is a web framework for Node.js. In versions 5.8.0 through 5.12.7, when the server is configured with a nonzero handlerTimeout and a route returns a streaming response, a request whose stream has already sent its headers but stays open past the timeout crashes the server. When the timeout fires, Fastify tries to send a new error response on a response that has already started, raising an uncaught ERR_HTTP_HEADERS_SENT that terminates the Node.js process and interrupts any other in-flight