The Bitcoin network faces a critical security warning ahead of a potential minority chain fork this weekend, driven by the activation of BIP-110. The immediate danger is not just price swings but a replay attack vulnerability that could lead users to inadvertently drain their own BTC wallets. Any transaction signed on the new fork to sell its coins can be copied and broadcast on the original Bitcoin chain, permanently moving real BTC to an attacker's address.
BIP-110 was designed to restrict non-payment data in Bitcoin transactions for one year. It included a two‑phase activation: first, a miner signalling period requiring 55% support (1,109 flagged blocks within 2,016-block window), and second, an unconditional trigger at block 961,632, where nodes running the software begin rejecting blocks that lack the required signal. Current signalling stands near only 2.6%, meaning virtually all blocks now mined would be rejected by BIP‑110 nodes once the activation point arrives—estimated for this weekend, though exact timing depends on block intervals.
Unlike the 2017 Bitcoin Cash split, which shipped with opt‑in replay protection, the BIP‑110 fork inherits Bitcoin’s transaction format without any mechanism to distinguish between chains. This leaves a gap that can be exploited: a buyer could offer an attractive price for the new tokens, obtain the signed transaction, and replay it on the main network to claim the same amount of BTC. Developer Kevin Loaec specifically warned that large holders are especially lucrative targets.
Exchanges face a delicate decision. Historically, platforms like Coinbase and Binance have delayed listing unprotected fork assets until replay safeguards are in place. The burden of safe handling now falls on individual users. The safest course is to do nothing: do not attempt to claim, sell, or transfer the forked coins from any wallet that also holds real BTC. Even coin‑control techniques to isolate balances require expert care and are not recommended for average holders.
Whether a lasting fork even materialises depends on miner activity post‑activation. Without miners building on the BIP‑110 branch, the chain could stall almost immediately. If it fails to gain liquidity, the replay risk may remain theoretical. However, a single exchange listing could trigger a wave of exploits. The episode underscores the need for standardised replay protection in any future upgrade that might create a parallel chain, intentionally or not.
