update changelog and bump version

CHANGELOG.md

@@ -1,8 +1,66 @@
 # Changelog
 
+## v0.33.6
+
+*July 1, 2020*
+
+This security release fixes:
+
+### Denial of service
+
+Tendermint 0.33.0 and above allow block proposers to include signatures for the
+wrong block. This may happen naturally if you start a network, have it run for
+some time and restart it (**without changing chainID**). Correct block
+proposers will accidentally include signatures for the wrong block if they see
+these signatures, and then commits won't validate, making all proposed blocks
+invalid. A malicious validator (even with a minimal amount of stake) can use
+this vulnerability to completely halt the network. 
+
+Tendermint 0.33.6 checks all the signatures are for the block with 2/3+
+majority before creating a commit.
+
+### False Witness
+
+Tendermint 0.33.1 and above are no longer fully verifying commit signatures
+during block execution - they stop after 2/3+. This means proposers can propose
+blocks that contain valid +2/3 signatures and then the rest of the signatures
+can be whatever they want. They can claim that all the other validators signed
+just by including a CommitSig with arbitrary signature data. While this doesn't
+seem to impact safety of Tendermint per se, it means that Commits may contain a
+lot of invalid data.
+
+_This is already true of blocks, since they can include invalid txs filled
+with garbage, but in that case the application knows they they are invalid and
+can punish the proposer. But since applications dont verify commit signatures
+directly (they trust tendermint to do that), they won't be able to detect it._
+
+This can impact incentivization logic in the application that depends on the
+LastCommitInfo sent in BeginBlock, which includes which validators signed. For
+instance, Gaia incentivizes proposers with a bonus for including more than +2/3
+of the signatures. But a proposer can now claim that bonus just by including
+arbitrary data for the final -1/3 of validators without actually waiting for
+their signatures. There may be other tricks that can be played because of this.
+
+Tendermint 0.33.6 verifies all the signatures during block execution.
+
+_the light client does not check nil votes and exits as soon as 2/3+ of the
+signatures are checked_
+
+**All clients are recommended to upgrade**
+
+Special thanks to @njmurarka for reporting this.
+
+Friendly reminder, we have a [bug bounty
+program](https://hackerone.com/tendermint).
+
+### SECURITY:
+
+- [consensus] Do not allow signatures for a wrong block in commits (@ebuchman)
+- [consensus] Verify all the signatures during block execution (@melekes)
+
 ## v.0.33.5
 
-Special thanks to our external contributor on this release: @tau3 
+Special thanks to our external contributor on this release: @tau3
 
 Friendly reminder: We have a [bug bounty program](https://hackerone.com/tendermint).
 

CHANGELOG_PENDING.md

@@ -1,4 +1,4 @@
-## v0.33.6
+## v0.33.7
 
 
 \*\*

version/version.go

@@ -21,7 +21,7 @@ const (
 	// XXX: Don't change the name of this variable or you will break
 	// automation :)
 
-	TMCoreSemVer = "0.33.5"
+	TMCoreSemVer = "0.33.6"
 
 	// ABCISemVer is the semantic version of the ABCI library
 	ABCISemVer  = "0.16.2"