Bitcoin Core developers have merged a privacy fix into the project's 32.x source branch to prevent observers from linking private broadcast connections to ordinary node activity. However, as of Oct. 8, the backport proposal to bring the fix to the 31.x release line remains open, leaving users on the current stable release, version 31.1, waiting for a patch.
Peer Discouragement Bug Details
The privacy issue centers on the opt-in privatebroadcast feature, which routes transactions via sendrawtransaction through dedicated, short-lived connections using Tor, I2P, or IPv4 and IPv6 peers over Tor. Under normal operation, Bitcoin Core employs a mechanism called discouragement to handle misbehaving peers on the network.
Before the update, discouraging a private-broadcast peer could trigger externally visible changes in node behavior or disconnect other connections tied to the same peer IP address. An observer monitoring network activity could leverage these shared disconnection patterns to link a user's private transaction broadcast directly to their main node address. The newly merged patch isolates these routines: private-broadcast peers are exempted from standard discouragement rules, while misbehaving private peers are still disconnected. Conversely, discouraging an ordinary peer no longer severs shared private connections.
Release Schedule and Backport Status
The original code change reached Bitcoin Core's main development branch on Sept. 25, followed by an initial backport submission on Oct. 1. On Oct. 6, reviewer vasild approved the backport proposal for the 31.x line, which carries a 31.2 milestone assignment. However, this milestone assignment does not establish an official release date.
Currently, the official download page lists 31.1 as the latest stable software version. Meanwhile, the 32.0 download directory contains release candidate testing files, including rc3 binaries dated Oct. 6. This repair follows an earlier fix detailed in the 31.1 release notes, which addressed an IP-address leak where private-broadcast submissions occasionally used clearnet instead of enabled privacy networks. Developers have since marked private broadcast as experimental and narrowed its privacy claims to risk reduction, even as overall network activity evolves alongside broader market developments like recent Bitcoin volatility and network halving progress.
Key Takeaways
- Code Merged: Bitcoin Core integrated a peer discouragement privacy fix into the 32.x branch following its Sept. 25 main branch merge.
- Pending Release: The 31.x backport with the 31.2 milestone received approval from vasild on Oct. 6, but remains open while 31.1 stays active.
- Mechanism: The patch prevents observers from linking private sendrawtransaction broadcasts over Tor or I2P to primary node IP addresses.
- Default Setting: Private broadcast is disabled by default and is classified as experimental.
Why It Matters
This update underscores the complex ongoing efforts required to maintain transaction origin privacy at the node level without creating secondary side-channel risks. By decoupling peer management routines between standard and private connections, developers eliminate a subtle tracking vector that could expose node operators using privacy routing protocols. For network participants demanding operational privacy, understanding these experimental boundaries and monitoring upcoming release candidates will be crucial as final builds roll out.
