Ravencoin is facing a potentially deep blockchain reorganization after a critical consensus vulnerability allowed an attacker to create invalid blocks without performing the full proof-of-work normally required by the network.
The Ravencoin project disclosed the incident on Aug. 11, and warned that the vulnerability had been exploited since Aug. 7. The first known invalid block appeared at height 4,487,776, and transactions confirmed after block 4,487,775 should be considered potentially reversible while the network recovers.
Mining pools 2Miners and RavenMiner are now building a chain that excludes the exploited branch. If that chain accumulates enough work to become dominant, Ravencoin warned that the network could undergo a reorganization covering approximately three days of blockchain history.
Ravencoin flaw allowed attackers to bypass KAWPOW
The vulnerability affects validation of Ravencoin's KAWPOW block headers. According to an emergency patch that was released by 2Miners, a block header contains an nHeight value that vulnerable nodes failed to verify against the block's actual position in the blockchain. An attacker could manipulate this value to reach a validation path that avoided normal KAWPOW proof-of-work verification.
That made malicious blocks dramatically cheaper to create than legitimate blocks requiring miners to perform the memory-intensive KAWPOW process.
2Miners said exploitation was observed between Aug. 7 and the release of its emergency software on Aug. 10. In one examined range of 2,089 blocks, the pool identified 96 affected blocks.
The vulnerability also created operational problems for the network. Affected nodes could fail after restarting, while nodes attempting to synchronize with the blockchain could encounter invalid header sequences and stop syncing.
Exchanges told to suspend Ravencoin transfers
2Miners released version 4.6.1.1-hf1 to reject blocks whose declared height does not match their real blockchain position from height 4,487,776 onward. The release also establishes block 4,487,775 as a checkpoint and includes logic for rebuilding corrupted chain state.
Ravencoin has urged exchanges to suspend RVN deposits and withdrawals until the network stabilizes and advised miners, exchanges, explorers and node operators to upgrade their software.
RVN’s price action over the past 24 hours (Source: CoinCodex)
The market reacted sharply to the uncertainty. At press time, RVN’s price traded near $0.00287, down roughly 19% over the past 24 hours.
The incident is particularly serious because it affected consensus rather than an individual wallet or application. Until the competing chain situation is resolved, even transactions that appeared confirmed during the affected period may not remain part of Ravencoin's eventual canonical blockchain.
