react/http is an event-driven, streaming HTTP client and server implementation for ReactPHP. Previous versions of ReactPHP’s HTTP server component contain a potential DoS vulnerability that can cause high CPU load when processing large HTTP request bodies. This vulnerability has little to no impact on the default configuration, but can be exploited when explicitly using the RequestBodyBufferMiddleware with very large settings. This might lead to consuming large amounts of CPU time for processing requests and significantly delay or slow down the processing of legitimate user requests. This issue has been addressed in release 1.9.0. Users are advised to upgrade. Users unable to upgrade may keep the request body limited using RequestBodyBufferMiddleware with a sensible value which should mitigate the issue. An infrastructure or DevOps workaround could be to place a reverse proxy in front of the ReactPHP HTTP server to filter out any excessive HTTP request bodies.