Fusaka upgrade in 1 month: Ethereum's boldest scalability gamble yet

Article by: Jason Nelson

Translation: Luffy, Foresight News

Summary

Ethereum will undergo the Fusaka upgrade in December 2025, bringing data scalability, DoS defense, and development tools.

PeerDAS (Peer Data Availability Sampling) increases blob throughput by 8 times by “sampling data instead of storing complete data on full nodes.”

New EIPs will set blob fees, limit block size, and introduce features such as pre-commitment and P-256 signature support.

The next major upgrade of the Ethereum network is imminent. Named Fusaka (an abbreviation of Fulu-Osaka), this upgrade is scheduled for December 2025 and will make significant adjustments to both the execution layer and consensus layer.

Fusaka is another milestone following Ethereum’s 2022 Merge. The 2023 Shapella upgrade introduced staked ETH withdrawals; the 2024 Dencun upgrade introduced prototype Danksharding technology and blobs; and the 2025 Pectra upgrade aims to enhance validator flexibility and Layer 2 interoperability.

According to the roadmap, the Fusaka upgrade aims to expand data capacity, strengthen defenses against DoS attacks, and introduce new tools for developers and users.

This upgrade has far-reaching implications. Fusaka is not a minor patch but a redesign of Ethereum’s data availability management, blob pricing, and transaction protection mechanisms. Its success will depend on whether Ethereum can achieve scalability to meet the growing demands of Layer 2 networks without causing network splits or overburdening node operators.

PeerDAS: Sampling Instead of Full Data Storage

The core feature of the Fusaka upgrade is PeerDAS, a new method for handling blobs.

In Ethereum, blobs are temporary data packets introduced with the Danksharding prototype during the Dencun upgrade. They allow rollups to submit large amounts of transaction data to the mainnet at low cost, improving scalability without permanently increasing the blockchain state.

This ensures redundancy, but as demand grows, it can create bottlenecks. Currently, every full node in Ethereum must store all blobs submitted to the chain.

PeerDAS changes this logic. Each node only needs to store about one-eighth of the blobs and relies on cryptographic reconstruction techniques to fill in missing data fragments. This design uses randomized sampling to verify data availability, with an error probability as low as 10²⁰ to 10²⁴.

Through this distributed storage approach, Ethereum can theoretically increase blob throughput by 8 times without requiring node operators to upgrade hardware or bandwidth. Rollups that publish compressed transaction data via blobs are expected to be the primary beneficiaries.

Economics and Flexibility of Blobs

The Fusaka upgrade also reshapes blob pricing and management mechanisms.

A key adjustment is EIP-7918, which introduces a minimum collateral fee for blobs. Under current rules, when execution layer gas fees dominate, blob prices can drop close to zero, leading to inefficient usage. The minimum collateral fee ensures a baseline cost for blob usage, forcing Layer 2 to pay for its storage and bandwidth consumption.

Another mechanism is EIP-7892, which introduces a soft fork that adjusts blob parameters. This allows Ethereum clients to modify blob throughput without a full hard fork, giving developers flexibility to respond to unpredictable Layer 2 demands without waiting for the next planned upgrade.

Enhanced Defense Against Attacks

Scalability also expands Ethereum’s attack surface. The Fusaka upgrade includes a series of adjustments to limit extreme cases and protect the network from DoS attacks:

EIP-7823: Limits the input size of the MODEXP operation to 8192 bits;

EIP-7825: Sets a gas cap of 2²⁴ units per transaction;

EIP-7883: Increases the gas cost for large exponents in MODEXP to better match computational effort.

EIP-7934: Limits execution layer block size to 10MB.

These adjustments collectively reduce the risk of client overload, propagation stalls, or network instability caused by extreme transactions or oversized blocks.

New Tools for Users and Developers

The Fusaka upgrade also aims to improve usability.

For users, EIP-7917 introduces pre-commitment support. This allows wallets and applications to preview validator proposal schedules, enabling users to lock in the certainty that their transactions will be included in subsequent blocks, reducing delays and uncertainty in transaction confirmation.

For developers, the upgrade adds two important features:

CLZ opcode, suitable for cryptographic algorithms and contract optimization;

EIP-7951, providing native secp256r1 (P-256) signature verification. This elliptic curve is commonly used in hardware devices and mobile systems, and its inclusion will enhance compatibility and account abstraction capabilities.

These adjustments aim to lower the barrier for application developers, paving the way for new wallet designs and security models.

What ETH Holders Need to Know

For ordinary Ethereum users, no action is required for the Fusaka upgrade. Account balances, tokens, and applications will continue to operate normally. The Ethereum official website emphasizes that users should beware of scams requesting ETH for upgrades or transfers; no such actions are necessary for the upgrade.

Responsibility mainly falls on validators and node operators, who must upgrade their execution and consensus layer clients in sync. Coordination is crucial: if validators do not upgrade simultaneously, the network could face downtime or temporary forks.

After a series of successful testnet activations, the Fusaka upgrade is scheduled to launch on the Ethereum mainnet on December 3, 2025.

The Future of Ethereum Post-Fusaka

Fusaka is one of the boldest initiatives in Ethereum’s roadmap since the Merge. It aims to simultaneously achieve three major goals: increasing blob capacity, strengthening defenses, and updating developer tools.

Testing and development are ongoing, with client teams focusing on PeerDAS performance, blob pricing models, and compatibility between execution and consensus layer software. If successful, Fusaka could become a turning point for Ethereum’s ability to handle the next wave of Layer 2 adoption and scalability improvements.