Bitcoin holders face a critical security risk this weekend as a fork tied to the BIP-110 proposal could create duplicate coin balances on two chains, exposing users who try to sell forked coins to replay attacks that also drain real BTC from the main network.
Kevin Loaec, a Bitcoin developer, flagged the danger on X on August 6. “In the next couple of days, a new shitcoin will fork off Bitcoin. It is a big security risk for people who just believe they will get an ‘airdrop’ and want to sell it, to get more bitcoin,” Loaec said.
How the Risk Emerges
BIP-110 proposes to restrict non-payment data, including pictures and text, from Bitcoin transactions for one year. Activating a change to Bitcoin’s rules requires miner agreement via block marking. The proposal has two activation routes: a standard 55% signalling threshold, now closed, and a mandatory-signalling rule that begins at block 961,632, expected this weekend.
At that block height, BIP-110 software will begin rejecting unmarked blocks. With miner signalling at only 2.6% as of Friday, a minority fork could produce blocks slowly or stall entirely, creating two separate chains and two versions of Bitcoin.
The Replay Attack Mechanism
Replay attacks occur when identical transactions broadcast on both chains allow a buyer to spend a fork-coin sale on the main Bitcoin chain, stealing real BTC in the process. Users who hold Bitcoin at the moment of the fork will receive equivalent balances on both chains, but selling those forked coins without proper precautions risks triggering the attack.
Replay protection, which prevents this cross-chain spending, is not built in until block 965,664, expected in early September. Until then, Bitcoin holders must manually separate their balances before spending safely on either chain.
The BIP-110 fork highlights the technical hazards that accompany minority proposals to change Bitcoin’s rules. Low miner participation means the fork could lack the network security and stability of the main chain, making any coins produced by it potentially worthless while still posing active risks to holders who attempt to liquidate them.
