Bitcoin Core to Patch Tor-Bypass IP Leak in v31.1 After Flaw Found in 31.0
Bitcoin Core developers have disclosed a privacy bug that can expose a node operator's public IP address under certain conditions when using the optional privatebroadcast feature introduced in Bitcoin Core 31.0. The issue was flagged on June 6 and publicly detailed in an advisory posted by the project on June 11, 2026, with a fix slated for release in version 31.1.
According to the project, the flaw is limited to privatebroadcast, a tool added in April 2026 with v31.0 to route messages through the Tor anonymity network so the receiving peer cannot determine where the message originated. The problem arises during an attempted encrypted connection using BIP324 v2. If that handshake fails, the client may automatically retry using the legacy v1 protocol. In that fallback path, the Tor proxy can be dropped, allowing the receiving node to record the sender's real IP address and infer an approximate location.
Developers warned the behavior could be triggered deliberately. A malicious peer could reject the initial encrypted handshake to force a plaintext reconnection, increasing the risk of linking identities because Bitcoin's transaction ledger is public. If an attacker associates a transaction with a specific IP address, they may be able to infer the owner of the funds.
The team said the issue does not affect the broader payment network for typical users. Standard wallet usage remains unaffected because it does not rely on the privatebroadcast feature. Researcher Eugene Siegel was credited for responsibly reporting the bug.
Until v31.1 is released, node operators who enabled the feature are advised to disable the privatebroadcast parameter or configure their setup so all outbound traffic is forced through Tor.
Markets showed little reaction to the disclosure. Bitcoin traded around $63,700 after the advisory circulated, with only minor changes in daily volume. Analysts noted the main impact is reputational, sharpening scrutiny of privacy-related networking features amid ongoing debates about governance and data relay mechanisms in the core software. The next key milestone is the official release of the patched update.
