Artificial intelligence from Octane Security has identified a serious flaw affecting the functionality of the Ethereum client Nethermind.

1/ Octane’s AI found a high-severity liveness bug in the @Nethermind execution client that could have stopped local block production for 38% of @ethereum mainnet validators.

This bug was patched via the @ethereumfndn bug bounty program, with no exploitation observed. pic.twitter.com/ebdUt31WC8

— Octane Security (@octane_security) February 25, 2026

According to the auditors, the vulnerability allowed for the halting of local block production for 38% of validators on the main network.

The issue arose due to a lack of length equality checks when validating transactions with large binary data arrays (BLOBs) in Nethermind during their inclusion in the pool.

Potential attackers could have created an invalid operation with BLOB objects, leading to missed slots with legitimate requests.

The problem was discovered during the integration of the Fusaka update, affecting both the testnet and mainnet.

The bug has already been fixed, and a thorough analysis found no attacks exploiting it.

“This is where automated security shines. Exceptional cases on the client side are hard to analyze manually, but they can be easily verified once detected [using AI],” representatives from Octane Security remarked to blockchain co-founder Vitalik Buterin.

The Ethereum Foundation confirmed the high severity of the issue, awarding the company a maximum reward of $50,000 as part of its bug bounty program.

It’s worth noting that in February, OpenAI, in collaboration with Paradigm, released a benchmark to assess the ability of AI agents to hack smart contracts.