This is a security fix release and is recommended for all users. It resolves a p2p vulnerability, and the fix is taken from the upstream geth client.
Some Other Changes are:
- miner: add dynamic gas limit adjustment by @cffls in #1979
- mainnet: Added Override StateSync Records Range by @pratikspatil024 in #1982
- v2.5.7 by @pratikspatil024 in #1984
Full Changelog: v2.5.6...v2.5.7