Bitcoin Core 31.1rc1 fixes privacy flaw before next mainnet release

Bitcoin Core released version 31.1rc1 on June 30, fixing a privacy flaw in PrivateBroadcast that could have exposed transaction origins on the network.

"PrivateBroadcast was designed to obscure transaction sources, but the implementation contained a flaw that could leak metadata linking transactions to their origin," the Bitcoin Core development team said in the release notes.

The fix prevents a class of metadata leakage that could have allowed network observers to correlate PrivateBroadcast transactions with their originating IP addresses, the team said. Version 31.1rc1 also introduces wallet performance improvements and validation enhancements ahead of the next stable mainnet release.

The disclosure followed responsible disclosure protocols, with no evidence the flaw was exploited in the wild. The release candidate now enters testing before the full mainnet deployment, with the stable release expected in the coming weeks.

The PrivateBroadcast feature, introduced in earlier versions of Bitcoin Core, allows users to broadcast transactions through randomized relay paths to obscure their network origin. Privacy researchers had flagged potential weaknesses in the implementation, leading to the audit that uncovered the flaw.

Bitcoin Core remains the dominant implementation of the Bitcoin protocol, running on an estimated 98 percent of reachable full nodes, according to Bitnodes. The update reinforces the network's privacy guarantees as blockchain surveillance tools from firms such as Chainalysis and TRM Labs have grown increasingly sophisticated. Other privacy-focused Bitcoin projects, including Wasabi Wallet and Samourai Wallet, have faced regulatory pressure in recent years, highlighting the importance of privacy features embedded directly in the reference client.

The wallet improvements in 31.1rc1 include faster transaction signing and reduced memory usage during initial block download, the team said. Validation changes tighten rules around transaction relay to prevent denial-of-service vectors identified during internal testing.

This article is for informational purposes only and does not constitute investment advice.