Ravencoin disclosed on Aug. 11 that a critical consensus vulnerability had been exploited since Aug. 7, allowing vulnerable nodes to accept invalid blocks beginning at height 4,487,776.
Summary
- Ravencoin said invalid blocks began at height 4,487,776 after a critical consensus vulnerability was exploited.
- 2Miners released an emergency patch rejecting forged blocks and advised every network operator to upgrade.
- Transactions confirmed after block 4,487,775 remain at risk if the recovery chain becomes dominant eventually.
- Upbit suspended RVN deposits and withdrawals after citing a network issue affecting Ravencoin on Monday.
- RVN fell 19.1% to about $0.00288 as traders reacted to the network security incident Tuesday.
The project warned in its notice that a recovery chain being mined by 2Miners and RavenMiner could trigger a deep reorganization spanning “approximately three days” if it becomes dominant.
The alert followed an emergency software release from 2Miners on Aug. 10. The pool said the flaw sits in KAWPOW block header validation and allows an attacker to bypass the normal memory intensive mining process. Ravencoin advised exchanges to halt RVN deposits and withdrawals and told users to treat confirmations after block 4,487,775 as potentially reversible.
Ravencoin bug allowed cheap invalid blocks
2Miners said the KAWPOW header contains an nHeight field that was not checked against a block’s actual position in the chain. By manipulating that value, an attacker could reach a validation path that skipped full proof of work verification and accepted a supplied mix hash without confirming genuine ProgPoW work.
The emergency release said blocks created through the flaw carried no genuine ProgPoW work and were “orders of magnitude cheaper” to produce than honest blocks at the same difficulty. It also documented two effects seen on mainnet: affected nodes could fail after restarting, while nodes attempting to synchronize could encounter broken header sequences and fail to catch up.
2Miners said exploitation continued from Aug. 7 through its Aug. 10 release. Between heights 4,489,527 and 4,491,615, it identified 96 affected blocks among 2,089 examined. A separate sample covering the period before Aug. 7 found no affected blocks, supporting the identified starting point.
2Miners ships emergency patch as recovery continues
2Miners released version 4.6.1.1-hf1, which rejects blocks whose declared header height differs from their actual chain position starting at 4,487,776. The patch also adds a checkpoint at 4,487,775 and rebuilds chain state when damaged index data prevents a node from continuing normally.
The pool said node operators, exchanges, miners and explorers should upgrade. Its release warns that the first restart can take several hours because the software replays about 4.49 million blocks and 28 million transactions while rebuilding chain state. Operators running several nodes were advised to upgrade them individually.
Ravencoin’s official GitHub notes separately said there was not yet a core version patching both the KAWPOW problem and a different asset transfer quantity overflow bug. Maintainer Hans Schmidt recommended using the 2Miners code for the mining problem until a combined patch becomes available.
Exchanges halt transfers as RVN falls 19%
Upbit suspended Ravencoin deposits and withdrawals on Aug. 10, citing a network issue, before the project’s broader warning. Its notice leaves trading available while transfers remain halted. Bitget also suspended RVN deposits and withdrawals for wallet maintenance beginning Aug. 10.
CoinGecko data showed RVN trading near $0.00288 on Tuesday, down about 19.1% over 24 hours. Its market capitalization had fallen to roughly $47.3 million while 24 hour trading volume approached $11 million.
Ravencoin has experienced a different protocol vulnerability before. In 2020, attackers exploited a flaw to create about 315 million unauthorized RVN, as crypto.news reported in earlier Ravencoin exploit coverage. The earlier incident involved excess token issuance, while the current vulnerability concerns proof of work validation and competing chain histories.
In related block reorganization coverage, an 18 block Monero reorg in 2025 invalidated previously confirmed transactions. The episode illustrates why exchanges often become cautious about transaction finality when proof of work networks develop competing histories.
What happens next for the Ravencoin chain
Ravencoin said 2Miners and RavenMiner controlled a majority of network hash rate and were mining from the last unaffected block while excluding the exploited branch. The project cautioned that if their chain becomes dominant, transactions confirmed after 4,487,775 may disappear from the accepted history. Some could return to mempools and be mined again, but Ravencoin said this is “not guaranteed.”
The next milestones are a stable dominant chain, wider adoption of patched software and a combined upstream Ravencoin release. Until then, the project’s guidance remains for exchanges to suspend transfers and for users not to rely on recent confirmations. Ravencoin also stressed that its warning should not be interpreted as support for a rollback or any particular recovery plan.
