Ethereum co-founder Vitalik Buterin has urged developers to make security the top priority after declaring that the contest to build faster zero-knowledge proofs is effectively over. In an October 15 post on X, Buterin congratulated the ZKsync Airbender team on its latest milestone and said the battle for speed had been definitively won, adding that work on zkEVMs should now shift fully toward security. zkEVMs are proving systems that generate cryptographic evidence that Ethereum transactions were executed under the network's rules, which makes their correctness directly relevant to how the chain verifies activity. The announcement has drawn attention to how zero-knowledge systems will be checked for correctness as they take on a larger role in Ethereum's transaction verification.

His remarks came two days after ZKsync introduced Airbender Prime on October 13. According to the project, a single NVIDIA RTX PRO 6000 Blackwell graphics card proved 99% of 7,200 consecutive Ethereum blocks in under 10 seconds, with every block in the tested set completing within 12 seconds. The reported timings included the proof preparation required for each block. ZKsync's X account promoted the release as real-time proving on one GPU, meaning proof generation fast enough to keep pace with block production — a benchmark that sat at the center of the speed race Buterin now considers definitively won.

Airbender is built on open-source software and relies on hash-based proofs, an approach the project says is designed to resist future quantum threats. Airbender Prime remains a ZKsync development, not an Ethereum network upgrade.

Buterin Outlines Three Security Requirements

Big congratulations to the @zksync airbender team for this milestone. At this point, I consider the battle for speed to be definitively won, and the top priority for zkEVMs should shift fully to security. To me that means formally verifying (i) equivalence of the… — vitalik.eth (@VitalikButerin) October 15, 2026

In the post, Buterin called for mathematical checks that establish whether proof calculations follow Ethereum's rules exactly. Formal verification — establishing a system's properties through mathematical proof rather than case-by-case testing — is widely treated as one of the most rigorous checks available for proving software. He also wants a strict upper limit on proving costs relative to block gas, Ethereum's measure of computational work per block, so that running proofs does not become prohibitively expensive for operators. His third requirement covers the security of the proof system itself. Buterin announced no timetable for these formal security checks.

The requirements carry weight because Ethereum plans to use more zero-knowledge proofs when verifying transactions. Such proofs let computers confirm results without repeating every calculation, which saves computational work but places a premium on correctness. High proving costs could also make participation harder for operators with limited hardware.

Separately, Buterin recently raised concerns about crypto wallet linked to advances in artificial intelligence.

Ethereum Price Nears Key Support Zone

Ethereum traded near $2,361 on October 15, according to a recent Ethereum price analysis. The report placed the day's low near $2,317 and identified the $2,300 to $2,350 range as an area traders were watching. The daily relative strength index stood near 34, reflecting weaker momentum.

ETH faced initial resistance between $2,400 and $2,450, followed by the $2,500 to $2,550 range. These market levels came from chart data rather than from Buterin's remarks, which focused on protocol development.

Spot Ethereum ETFs Record $19.7 Million in Outflows

U.S. spot Ethereum funds recorded $19.7 million in net outflows on October 14. That followed recent ETF withdrawals during the previous week. Separate market data showed heavy liquidations across cryptocurrency futures as prices declined.

ZKsync's speed figures come from its own tests, while Ethereum developers still face the separate task of confirming proof accuracy and controlling computing costs.