Ethereum developers have confirmed that the public test of the Glamsterdam upgrade is set for October 6, 2026. The announcement came during a core developer call.

At the same time, the team flagged a vulnerability in the Sepolia testnet tied to the new block auction system.

The Vulnerability Explained

A potential attacker could spin up a bunch of fake “developer” identities, outbid legit auction participants, and then refuse to relay transactions after winning. This risk is specific to how block auctions work in Sepolia right now.

Glamsterdam Test: Mark Your Calendar

The public test goes live on October 6, 2026. The main goal: stress-test how the new block auction system performs on the Sepolia testnet.