Bitcoin Core 32.0 Release Candidate Includes Speed Improvements and Security Fixes

Bitcoin Core 32.0 has entered its release candidate phase following improvements to block validation speed and security vulnerability fixes. The development team set an initial target for the official version release on October 10, 2026, though this date may change based on final testing results. The core focus of this update is a new feature allowing parallel retrieval of transaction inputs required for block verification across multiple threads, with default 8 threads and a maximum of 16 configurable. Benchmark tests showed initial block download (IBD) speeds improved by 1.18x to over 3x depending on hardware, storage, and cache settings, though not all nodes will see identical speed gains.

The changes aim to reduce the time required for initial synchronization by parallelizing repetitive disk read operations during IBD, without altering block generation rates or consensus rules. The development team confirmed that verification logic and consensus behavior remain unchanged. Wallet functionality also sees updates, with some wallet commands now defaulting to a new format for partially signed Bitcoin transactions (PSBT). Hardware wallets and separate signing devices will need compatibility checks due to this change, though existing request paths are maintained.

Security patches include fixes for an issue on non-Windows systems where authenticated users could execute commands via specific wallet names combined with the walletnotify feature. The walletnotify function triggers external commands upon wallet transactions, though no confirmed exploitation cases were disclosed. Additional fixes address a memory exhaustion vulnerability in the new HTTP server, which saw memory usage drop from 3.2GB to approximately 3MB under similar test conditions. This patch was merged on September 5 after being identified during an audit involving the Kimi K3 AI model.

The update is more relevant to node operators, wallet developers, and transaction processing services than general users. Further release candidate testing, wallet compatibility checks, and additional security reviews are planned before the official version launch.