Bref enable serverless PHP on AWS Lambda. When Bref is used with the Event-Driven Function runtime and the handler is a "RequestHandlerInterface", then the Lambda event is converted to a PSR7 object. During the conversion process, if the request is a MultiPart, each part is parsed and its content added in the "$files" or "$parsedBody" arrays. The conversion process produces a different output compared to the one of plain PHP when keys ending with and open square bracket ([) are used. Based on the application logic the difference in the body parsing might lead to vulnerabilities and/or undefined behaviors. This vulnerability is patched in 2.1.13.