Ethereum contributors have officially set October 6 as the testing date for the anticipated “Glamsterdam” upgrade, though the announcement came alongside a severe warning that malicious actors using counterfeit credentials could disrupt the network dry run.
Core developers cautioned that virtually anyone—even a youth equipped with complimentary test ether and a few bogus profiles—could continuously secure the blockchain’s block auction rights for incoming transaction batches. Afterward, the wrongdoer could simply ghost the system by withholding the necessary data, effectively halting network operations.
This vulnerability is significant because a frozen traffic environment makes it difficult for programmers to evaluate how the upgrade manages authentic workloads. The October 6 launch serves as a preliminary public dry run ahead of the final Glamsterdam rollout, which will proceed only after engineers confirm complete operational safety.
“I can just spin up a thousand builders, rotate them, offer very high bids, and not produce payloads,” Ethereum consensus developer Potuz noted during Thursday’s core developer call. “Any teenager can do this.”
Such an offensive maneuver would present no risk to mainnet capital. Any potential disruption would solely impact “Sepolia,” where test ether holds zero real-world value, yet it could leave blocks devoid of transaction data and derail vital infrastructure evaluations prior to Glamsterdam’s integration into Ethereum proper.
What is Glamsterdam?
Glamsterdam represents Ethereum’s next major protocol enhancement, engineered to pack increased activity into every block without overloading validating computers. Alongside adjustments to gas economics, this patch aims to accommodate a block gas ceiling near 200 million, expanding capacity for additional transfers and exchanges before user fee bids escalate.
This upgrade embeds the interaction between validators and specialized block producers directly into the Ethereum framework. Producers compile transaction sets and vie to deliver them, and once a validator accepts the winning bid, the producer is expected to disclose the underlying instructions.
Naturally, this mechanism proves vulnerable to exploitation on a zero-cost test network. A bad actor can submit bids far surpassing any legitimate competitor, secure consecutive victories, and subsequently conceal the committed payload.
Engineers pointed out that standard defenses typically revert to locally generated blocks only after multiple payloads fail to materialize.
Potuz further explained that client software must actively detect and ban individual operators so that an attacker cannot reappear under an alternate profile to maintain their winning streak.
This advisory arrived one day after a comprehensive private test successfully executed the Glamsterdam transition, elevating its block gas limit toward 200 million without compromising network finality.
Read More: Ethereum’s upcoming Glamsterdam upgrade clears rehearsal for a big jump in capacity
Software implementation teams now face a September 29 deadline to deliver Sepolia-compatible releases. This provides a seven-day runway before the fork, cutting the standard 14-day window typically allocated for security checks and bug bounty programs in half.
Developers accepted this compressed schedule because Sepolia features a relatively centralized structure that simplifies recovery if errors surface. Furthermore, production producer software managed by groups like Titan and Ultrasound has yet to finish a Glamsterdam fork conversion, introducing another hurdle before the upgrade can be deemed mainnet-ready.
The subsequent public evaluation on Hoodi is provisionally scheduled for October 27. Programmers will evaluate whether to maintain that timeline following observations from Sepolia, while an official mainnet release date remains unannounced.
Originally published at https://www.coindesk.com/tech/2026/09/18/ethereum-confirms-glamsterdam-dates-but-warns-fake-builders-could-stall-the-chain.
