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Bitcoin Core is heading into its final stretch before a major release. The first release candidate for version 32.0 got tagged on September 14, with October 10 set as the target drop date per the project’s release schedule.
It’s a bigger update than the version number might suggest. Fee estimation, security, memory management, transaction formats, server infrastructure — developers touched pretty much all of it. And some of what they found during testing was genuinely alarming, particularly around memory consumption in the new web server. More on that in a moment.
How Fee Estimation Changes in Version 32
Right now, Bitcoin Core estimates transaction fees by looking at what got paid in previous blocks. That’s the whole system. It works, but it’s kind of blunt — it doesn’t account for what’s sitting in the mempool waiting to confirm.
Version 32 adds a second estimator that watches those pending transactions directly. The dual-estimator setup means users could end up paying lower fees when network congestion drops off, because the software will have a clearer, more current picture of what’s actually needed to get a transaction through. Not a dramatic overhaul of how Bitcoin works, but a meaningful quality-of-life improvement for anyone paying close attention to their fee spend.
Nodes will also fetch transaction data faster. The update enables multi-threaded data retrieval, with eight threads running by default. Less waiting around for data to load.
Security Flaw Fixed, PSBT Format Updated
There’s a security fix baked into version 32 that probably deserved more attention than it got. A flaw introduced back in Bitcoin Core 24.0 — affecting non-Windows systems — let malicious commands execute through specially crafted wallet names. Basically, if someone could feed a node a wallet name built to exploit the vulnerability, they could run arbitrary commands. Bad. Version 32 now treats wallet names as literal text, which closes that off.
Bitcoin Core 32 also moves to PSBT version 2 — the newer format for partially signed transactions. PSBT is how wallet software and signing devices talk to each other when building a transaction that needs multiple parties or devices to sign off. The version 2 format is cleaner and more capable than the original. But the shift means any application or service built directly around Bitcoin Core’s PSBT commands needs to verify compatibility. Developers did leave the older format available for apps that request it, so it’s not a hard cutoff. Still, services that haven’t tested against the new format probably should before October 10.
The Memory Bug That Sent Usage From 46 MB to 3.2 GB
Here’s where things got genuinely concerning during testing. Bitcoin Core 32 replaces the existing web server with a new implementation. During pre-release auditing — done with Moonshot AI’s Kimi K3 model — testers found a memory exhaustion issue in the new server.
The problem: data from clients was piling up in memory faster than the server could process it. In a 90-second test, 16 unauthenticated REST connections pushed a node’s memory from 46 MB to roughly 3.2 GB. That’s not a slow creep — that’s a spike. Left unaddressed, that kind of behavior could crash a node or make it unusable.
The REST interface had a related problem. A separate test showed memory climbing from 46 MB to approximately 3 GB in just one minute under similar unauthenticated connection load.
After the fix, the same test produced memory usage of around 3 MB. That’s a pretty dramatic turnaround. Both issues were caught and resolved before the stable version ships, which is exactly what pre-release testing is supposed to do — but it’s a reminder of how much can go wrong when you swap out core infrastructure.
Developers spent real time making sure the new server handles requests efficiently without letting memory balloon uncontrollably. The old server had the same basic flaw — data accumulation outpacing processing — and the new one nearly shipped with it too.
For node operators, the practical upshot is better stability and more predictable resource use once version 32 lands. For developers building on top of Bitcoin Core, the PSBT format change is the main thing to check before the October 10 release. Applications can still request the older transaction format if needed, so backward compatibility isn’t gone — but it’s not guaranteed to be seamless without testing.
The release candidate is live now. Anyone running Bitcoin Core infrastructure probably wants to be in that testing pool rather than waiting for the stable drop.
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Frequently Asked Questions
What security vulnerability does Bitcoin Core 32 fix?
A flaw from Bitcoin Core 24.0 on non-Windows systems allowed malicious commands to run through specially crafted wallet names. Version 32 fixes this by treating wallet names as literal text.
How bad was the memory bug found during Bitcoin Core 32 testing?
During testing, 16 unauthenticated REST connections pushed a node’s memory from 46 MB to roughly 3.2 GB in 90 seconds. After the fix, the same test resulted in about 3 MB of memory use.
Why It Matters
The upcoming release of Bitcoin Core 32.0 is significant as it addresses critical issues related to fee estimation and memory management, which can directly impact transaction efficiency and network performance. As Bitcoin continues to evolve in a competitive landscape, improvements in these areas are essential for maintaining user confidence and enhancing the overall utility of the network, particularly during periods of high transaction volume. Additionally, addressing security concerns reinforces the integrity of the Bitcoin ecosystem, which is crucial for its long-term adoption and stability in the market.
