Bitcoin Core had a wallet-migration bug in versions 30.0 and 30.1

The consensus rules did not blink. A folder on a disk did. In versions 30.0 and 30.1, Bitcoin Core shipped a wallet-migration bug that, under rare conditions, could delete unrelated files in a wallet directory. A later optional feature, private broadcast in 31.0, could reveal the sender's IP address after a failed encrypted handshake. Those are not the same bug, and neither is a failure of Bitcoin the protocol. They are wallet tooling, optional flags, file operations, and delayed disclosure behaving as their own security surface.

The project's January 5, 2026 advisory is specific. "Under rare circumstances, when the migration of a wallet.dat file fails, all files in the wallet directory may be deleted in the process, potentially resulting in a loss of funds." The condition set is narrow: a default unnamed wallet.dat, not created by default since 0.21, that fails to migrate or load, sometimes when pruning ran while the wallet was unloaded. Binaries for the affected releases were pulled from bitcoincore.org. Users were told not to attempt migrations until 30.2. "All other users, including existing wallet users, are unaffected and can keep using existing installations." That sentence is the opposite of a chain halt. It is also a reminder that a rare file-operation bug can still empty a drawer that held more than one wallet.

The privacy bug is a broken promise, not a consensus bug. Bitcoin Core 31.0 introduced `-privatebroadcast`. The 31.0 notes said a sender's IP address "is never known to the recipients." The June 6, 2026 advisory said that guarantee failed when a v2 (BIP324) handshake died and the node retried as v1 without the Tor proxy, connecting directly over clearnet. Onion and I2P peers were unaffected. Initial v1 connections that never tried v2 were unaffected. The leak was the retry path. Version 31.1, released July 8, 2026, fixed the proxy handling. The project's software life cycle lists 31.x as a major line released April 19, 2026, with 30.x still in the maintained window until a later major ships. The canonical releases index, not a third-party download page, is how a reader checks which binary is current. Self-custody users and node operators can lose privacy or files when a feature behaves differently from its promise. Service providers face broader exposure because one release or configuration can affect many customers. Developers have to balance prompt warning, safe fixes, and enough time for operators to update before a detailed write-up helps attackers. Users bear backup and upgrade complexity. Protocol consensus, operator configuration, user backups, and any custodial wrapper around a hosted wallet are four layers. Coverage has to state affected versions, required settings, known exploitation, fix version, backup guidance, and confidence level, and then stop. Improvising recovery steps beyond official instructions is how a software note becomes a second incident. Public advisories do not always say whether an issue was exploited, how many operators used the feature, or how quickly services upgraded. Different maintained branches can carry different fixes. That uncertainty is a closing beat. The standing product is a release ledger: discovery, private report, fix, release, disclosure, observed exploitation, end of life, with checksums and official notes. Scare headlines about "Bitcoin" collapse those steps into a protocol claim the advisories do not make. The wallet is software. Software fails in folders and flags. Report it that way.