Logstash Nested Compression Recursion.Security

The logstash source now rejects compressed frames that are nested inside other compressed frames. Previously, a malicious sender could nest compressed (C) frames arbitrarily deep, driving unbounded recursion in the decoder until the process exhausted its stack and aborted. Compressed payloads may now contain only a single layer of compression; no known Lumberjack/Beats client (e.g. Filebeat) ever emits more than one.

authors: thomasqueirozb