changelog for v4.2.0 (#793) (#795)

CHANGELOG.md

@@ -36,6 +36,20 @@ Ref: https://keepachangelog.com/en/1.0.0/
 
 ## [Unreleased]
 
+## [v4.2.0] - 2021-03-25
+
+A critical security vulnerability has been identified in Gaia v4.1.x.
+User funds are NOT at risk; however, the vulnerability can result in a chain halt.
+
+This release fixes the identified security vulnerability.
+
+If the chain halts before or during the upgrade, validators with sufficient voting power need to upgrade
+and come online in order for the chain to resume.
+
+### Bug Fixes
+
+* (sdk)  Bump SDK version to [v0.42.3](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.42.3)
+
 ## [v4.1.2] - 2021-03-22
 
 This release removes unnecessary dependencies.
@@ -82,7 +96,7 @@ IBC UpdateClient message event.
 ### Bug Fixes
 
 * (tendermint) Bump Tendermint version to [v0.34.8](https://github.com/tendermint/tendermint/releases/tag/v0.34.8).
-* (sdk)  Bump SDK version to [v0.41.4](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.41.4).
+* (sdk)  Bump SDK version to [v0.41.4](https://github.com/cosmos/cosmos-sdk/releases/tag/v0.41.4), which reduces startup time with the cosmoshub-4 mainnet genesis without invariant checks. 
 
 ## [v4.0.4] - 2021-02-19
 
@@ -307,7 +321,8 @@ See the [Tendermint v0.34.7 SDK changelog](https://github.com/tendermint/tenderm
 
 <!-- Release links -->
 
-[Unreleased]: https://github.com/cosmos/gaia/compare/v4.1.2...HEAD
+[Unreleased]: https://github.com/cosmos/gaia/compare/v4.2.0...HEAD
+[v4.2.0]: https://github.com/cosmos/gaia/releases/tag/v4.2.0
 [v4.1.2]: https://github.com/cosmos/gaia/releases/tag/v4.1.2
 [v4.1.1]: https://github.com/cosmos/gaia/releases/tag/v4.1.1
 [v4.1.0]: https://github.com/cosmos/gaia/releases/tag/v4.1.0