BitMEX Research Warns BIP-444 Could Incentivize On-Chain CSAM and Double-Spend Attacks

A recent proposal, BIP-444, has sparked considerable debate in the Bitcoin community about the network’s security and core principles. Critics warn that it could alter how Bitcoin handles data in ways that introduce serious new security risks.

The proposal’s author argues that these changes are necessary because Bitcoin Core 30 currently requires extensive data to be stored in transactions, which they describe as a critical issue. To address this, BIP-444 proposes an emergency soft fork that would retroactively fix the problem. However, many experts caution that this approach could create more risks than it solves.

BitMEX Research Slams the Proposal 

BitMEX research warned that the proposal could create a dangerous new incentive for attackers to put illegal content on Bitcoin’s ledger.

The BIP 444 proposal is incredibly bad

A bad actor who wants to conduct a double spend attack, could put CSAM onchain to cause a re-org and succed with their attack

The proposal therefore provides an economic incentive for onchain CSAM pic.twitter.com/7XZ6uocjMR

— BitMEX Research (@BitMEXResearch) October 26, 2025

The researchers argue that some nodes or miners might refuse to process a block or treat it differently. Meanwhile, other nodes could update to the new rule at the same time. This split in the network would give malicious actors the opportunity to deliberately include child sexual abuse material (CSAM). Attackers could also exploit this process to trigger a chain reorganization (reorg). This would allow them to execute double-spend attacks and spend the same Bitcoin twice.

Beyond these attack risks, BIP-444 raises another major concern: it would break Bitcoin’s immutability. The blockchain is meant to be permanent, but the proposal suggests a retroactive fix that could alter past blocks. Many see this as a dangerous precedent that weakens trust in the network’s history and permanence.

Censorship Concerns Grow

Critics argue that the proposal encourages censorship. The proposal allows developers or miners to decide which data can be stored on the blockchain. This creates centralized control, directly conflicting with Bitcoin’s core principle of censorship resistance and neutrality.

Supporters of BIP-444, however, say the proposal aims to protect node operators from legal exposure and prevent excessive data from overloading node storage. They argue that temporary limits could buy time to design better long-term rules. Opponents counter that imposing limits at the protocol level hands the power to decide what content is acceptable. They warn that this power could easily be weaponized.