We have released version 2.6.2 of the stream-collector
This patch release is simply to generate new docker images that bring in a sufficiently recent version of openssl, see here.
If you are already using a recent version of the collector, then upgrading is as simple pulling the most recent docker image
docker pull snowplow/scala-stream-collector-kinesis:2.6.2 docker pull snowplow/scala-stream-collector-pubsub:2.6.2 docker pull snowplow/scala-stream-collector-kafka:2.6.2
The Snowplow docs site has a full guide to setting up and running the collector.