I've prepared artifacts for the release of Apache POI 3.17 (RC3).
The most notable changes in this release are:
- Various modules: add sanity checks and fix infinite loops / OOMs caused by fuzzed data
- OPC: fix linebreak handling on XML signature calculation (#61182)
- SS Common: fix number formatting (github-43/52, #60422)
- SXSSF: fix XML processing - unicode surrogates and line breaks (#61048, #61246)
I'll add the summary to the change log on releasing the artifacts.
This will be the last release for Java 6 - the next release will be 4.0.0 for Java 8 
Please vote to release the artifacts.
The vote keeps open for 72hrs, 2017-09-13, 23:59 UTC,
planned release announcement date is Saturday, 2017-09-16.
Here is my +1