Local disclosure via insecure temp files

Information disclosure in Netty netty-codec-http before 4.1.77.Final allows local users to read uploaded data via temporary files. Multipart decoders create disk-backed temporary files with permissions readable by other local users when the default temporary directory is used, because the Java 6 code path leaves files broadly readable. Exploitation requires Java 6 or lower, disk-backed multipart uploads, and a Unix-like or very old macOS or Windows system sharing its temporary directory; the consequence is local confidentiality loss only.