GHSA-MJQX-C6F6-7RC2 mint: Content-Length header accepts non-RFC "+" sign prefix

Summary Mint's HTTP/1 client accepts Content-Length header values with a leading + sign e.g. +0, +123, which RFC 7230 forbids Content-Length = 1DIGIT. On a connection shared with a strict fronting proxy or load balancer, this parser disagreement is a response-smuggling primitive: the proxy frames...