Dash Core 0.12.3.3 is a critical bugfix release of the Dash Core 0.12.3.x series.
There was a serious vulnerability discovered in Bitcoin Core’s codebase recently which can cause node receiving a specially crafted block to crash https://github.com/bitcoin/bitcoin/pull/14247
We encourage all full node operators (masternodes, mining pools, explorers, exchanges etc.) to update ASAP.
Full release notes are available at https://github.com/dashpay/dash/blob/v0.12.3.3/doc/release-notes.md, release binaries can be downloaded from https://github.com/dashpay/dash/releases/tag/v0.12.3.3.