Bitcoin Core developers have disclosed a privacy vulnerability affecting users of the optional private broadcast feature.
The bug sits in the privatebroadcast function, which was added to Bitcoin Core 31.0 in April this year.
Under certain network conditions, the flaw can reveal a node operator’s IP address to the receiving peer.
This directly undermines the privacy guarantee the feature was designed to provide for transaction broadcasters.
The issue arises when a node attempts to establish an encrypted BIP324 v2 connection with a peer.
If that handshake fails, the connection can fall back to an unencrypted route and bypass Tor.
This fallback is what exposes the originator’s public IP address to the receiving node.
Developers say the bug is most likely triggered by a malicious peer deliberately breaking the v2 handshake.
Only node operators running version 31.0 who have enabled the privatebroadcast option are affected.
Regular wallet users, exchange customers, and miners are not impacted by this issue at all.
A permanent fix is scheduled for release in version 31.1, though no firm date has been confirmed.
Until then, the development team has recommended several workarounds for affected users.
Operators can disable the privatebroadcast feature entirely, or turn off v2 transport using the v2transport setting.
Another option is routing all outbound peer to peer traffic through Tor as an added safeguard.
Each workaround carries tradeoffs, including making nodes easier to fingerprint or more exposed to Sybil attacks.
The Bitcoin Core team published technical details and the recommended mitigations directly through its official channels.
Bitcoin’s price showed little reaction to the disclosure, trading broadly steady in the mid sixty thousand dollar range.
The episode adds to a string of recent scrutiny over how Bitcoin Core handles privacy related code changes.
It also reopens debate among node operators about who oversees and audits changes to the core software.
For now, the fix remains a priority item on the development team’s roadmap ahead of the next release.
