GO-2025-3638 ServerHellos are accepted without checking TLS 1.3 downgrade canaries in github.com/refraction-networking/utls

Before version 1.7.0, utls did not implement the TLS 1.3 downgrade protection mechanism specified in RFC 8446 Section 4.1.3 when using a utls ClientHello spec. This allowed an active network adversary to downgrade TLS 1.3 connections initiated by a utls client to a lower TLS version e.g., TLS 1.2...