Critical Bug Report

MWC Team

March 18, 2021

On March 18, 2021 a GRIN developer contacted the MWC development team with a critical bug report related to the rangeproof caching logic and the GRIN developers recommended not using the network until a fix had been safely implemented[ 26].

MWC exchanges were immediately notified about this critical bug and requested to halt trading, deposits and withdraws.

The GRIN network was affected and a fix [ 13] was implemented with a rewind of the blockchain.

Unfortunately, these types of unexpected events have happened in Bitcoin and other distributed consensus networks [ 7].

Because MWC is a fork of GRIN, it therefore contained the same bug. The MWC development team is implementing a similar fix; however, it may take slightly longer to take complete effect. The rewind will take place at block 693,000 which was on March 13th. Any transactions before that block will be unaffected.

Consequently, following the example of the GRIN developers the MWC developers recommend not using the MWC network until a fix has been safely implemented. The rewind is expected to affect about six days of the blockchain. The plan is for legitimate transactions, to the extent possible, to be included so end users are not significantly affected.

The fix, rewind, testing and implementation are expected to take a few days. Users will be able to download an updated version of the wallet to get the rewind to take effect sooner. After that it may take up to a week for users with non-upgraded nodes to get a correction to their transaction history.

We salute all of the warriors for monetary sovereignty and finding and fixing these bugs. This is hard work!