Ravencoin faces four-day rollback after consensus flaw

Ravencoin is confronting the prospect of a deep blockchain reorganisation that could reverse several days of transactions after a critical software vulnerability allowed invalid blocks to enter its ledger.

Two of the network’s largest mining pools, 2Miners and RavenMiner, are building an alternative chain from block 4,487,775, the last block before the first known invalid block appeared on August 7. Together, the pools control a majority of Ravencoin’s computing power, increasing the likelihood that their replacement chain could become the version ultimately accepted by the network.

Such an outcome could remove transactions confirmed after 15:44 UTC on August 7. Payments, exchange deposits and withdrawals made during the affected period could disappear from Ravencoin’s recognised history. Some transactions might return to the network’s pool of unconfirmed transactions and be processed again, although there is no guarantee that this would happen automatically.

The first identified invalid block was recorded at height 4,487,776. The vulnerability affected Ravencoin’s KAWPOW proof-of-work validation and allowed specially constructed blocks to bypass checks that should have rejected them.

The flaw involved a block-header field containing the declared block height. Under the vulnerable implementation, that value was not adequately checked against the block’s actual position in the chain. Manipulating the field could cause affected software to follow a validation path that failed to perform the full proof-of-work verification required under the network rules.

That weakness effectively meant an attacker could cause some Ravencoin nodes to accept blocks that had not satisfied the computational conditions governing legitimate mining. Additional invalid blocks appeared after the first exploitation, complicating efforts to identify an uncontested point from which the blockchain could safely continue.

2Miners released an emergency software patch, version 4.6.1.1-hf1, designed to reject blocks where the declared height differs from their actual position. The patch also introduced a checkpoint at block 4,487,775, effectively anchoring participating nodes to the last known unaffected block.

Applying the patch can require nodes to rebuild substantial parts of their chain data. Ravencoin has processed more than 4.4 million blocks and tens of millions of transactions since launch, making reconstruction a potentially demanding operation for network operators.

RavenMiner said it was running the emergency fix and mining what it described as a clean chain. The pool suspended payouts while the competing chains are resolved and said mining rewards earned during the disputed period could be affected. Earnings preceding the first invalid block remain outside the contested window.

Ravencoin itself has warned users, miners, exchanges and infrastructure operators about the consensus vulnerability while stopping short of formally endorsing a specific rollback strategy. The project sought a recovery point that would place less transaction history at risk, but the dominant mining pools continued rebuilding from the block immediately preceding the first identified exploit.

The situation illustrates the influence that concentrated hashpower can exert on smaller proof-of-work networks. Bitcoin operates under a similar broad principle in which miners compete to extend the chain carrying the greatest accumulated work. Ravencoin, however, has far less total computing power and a more concentrated mining distribution, allowing a small number of pools to have greater influence during a chain split.

Cryptocurrency exchanges moved to reduce their exposure as uncertainty developed. Upbit suspended Ravencoin deposits and withdrawals and placed an investment warning on RVN trading markets. Bitvavo also halted transfers, while other platforms introduced restrictions or maintenance measures while waiting for the network to stabilise.

The precautions are significant because exchanges could incur losses if they credited deposits that later disappear from the accepted blockchain. A customer could theoretically deposit RVN, trade or withdraw another asset, and then see the original Ravencoin deposit removed from chain history during a deep reorganisation.

RVN fell sharply as the vulnerability became public, trading around $0.0028 to $0.0029 on Tuesday. The decline exceeded 20% at points during the session, while trading activity rose substantially as holders reacted to uncertainty surrounding transaction finality and the network recovery process.

Ravencoin was launched in 2018 as a fork of Bitcoin’s code and is designed primarily for issuing and transferring digital assets. Its maximum supply is 21 billion RVN, compared with Bitcoin’s 21 million-unit ceiling.