Bitcoin Optech Newsletter #373

Bitcoin Optech Newsletter #373 is here:

- summarizes a vulnerability affecting old versions of Eclair
- summarizes research into full node feerate settings
- summarizes popular Q&A from Stack Exchange
- Optech Newsletter #373 Podcast

https://bitcoinops.org/en/newsletters/2025/09/26/

Matt Morehouse posted to Delving Bitcoin to announce the responsible disclosure of a vulnerability affecting older versions of Eclair...

https://bitcoinops.org/en/newsletters/2025/09/26/#eclair-vulnerability

Daniela Brozzoni posted to Delving Bitcoin the results of a scan of almost 30,000 full nodes that were accepting incoming connections...

https://bitcoinops.org/en/newsletters/2025/09/26/#research-into-feerate-settings

Selected Q&A from Bitcoin Stack Exchange:

- Implications of OP_RETURN changes in upcoming Bitcoin Core version 30.0?
- If OP_RETURN relay limits are ineffective, why remove the safeguard instead of keeping it as a default discouragement?
- What are the worst-case stress scenarios from uncapped OP_RETURNs in Bitcoin Core v30?
- If OP_RETURN needed more room, why was the 80-byte cap removed instead of being raised to 160?
- If arbitrary data is inevitable, does removing OP_RETURN limits shift demand toward more harmful storage methods (like UTXO-inflating addresses)?
- If OP_RETURN uncapping doesn’t increase the UTXO set, how does it still contribute to blockchain bloat and centralization pressure?
- How does uncapping OP_RETURN impact long-term fee-market quality and security budget?
- Assurance blockchain will not suffer from illegal content with 100KB OP_RETURN?
- What analysis shows OP_RETURN uncapping won’t harm block propagation or orphan risk?
- Where does Bitcoin Core keep the XOR obfuscation keys for both block data files and level DB indexes?
- How robust is 1p1c transaction relay in bitcoin core 28.0?
- How can I allow getblocktemplate to include sub 1 sat/vbyte transactions?

https://bitcoinops.org/en/newsletters/2025/09/26/#selected-qa-from-bitcoin-stack-exchange

Bitcoin Optech will host an audio recap discussion of this newsletter on Riverside.fm Tuesday at 16:30 UTC. Join us to discuss or ask questions!

https://riverside.fm/studio/bitcoin-optech