Executive Summary

• The Fusaka upgrade, scheduled for mainnet activation on 3 December 2025, represents Ethereum’s next major milestone following the Pectra upgrade in May. Fusaka’s 13 EIPs can be grouped into three objectives: scaling Layer-2s (L2s), improving Layer-1 (L1) execution efficiency, and enhancing user and developer experience.
• Fusaka increases L1 throughput through four specific pathways:
• • Gas Limit Increase (EIP-7935): Ethereum’s available block gas limit will rise from 45 million to 60 million, expanding computation and transactions per block and increasing L1 execution capacity.
  • Transaction Gas Limit Cap (EIP-7825): Setting a cap for per-transaction gas improves block composability, guarantees more transactions per block, and supports more predictable throughput.
  • MODEXP Gas Repricing (EIP-7883): Updating the costs and limits for the Modular Exponentiation (MODEXP) precompile prevents transaction spam, contributes to stable, predictable throughput for the Ethereum L1, and supports future gas limit increases.
  • Network Protocol Optimisation (EIP-7642): Improving inefficiencies at the network layer reduces bandwidth requirements and prepares Ethereum for future execution improvements.
• Fusaka scales L2 and enables fee reduction through: 
• • Peer Data Availability Sampling (PeerDAS) (EIP-7594): PeerDAS lowers per-validator load and allows the network to support larger blob capacity without increasing hardware requirements.
  • Blob Parameter Only (BPO) Hard Forks (EIP-7892): This mechanism enables Ethereum to raise blob throughput quickly and predictably, providing rollup teams with clear visibility into future capacity increases.
• Looking ahead, the next major upgrade after Fusaka is Glamsterdam, — expected in the first half of 2026 — and is anticipated to improve Ethereum’s censorship resistance, Maximum Extractable Value (MEV) transparency, and user experience. Ethereum’s roadmap also involves a stronger emphasis on privacy. Vitalik Buterin recently unveiled details on Kohaku, an open-source, privacy-focused framework designed to make privacy-preserving wallets and its software development kit (SDK) developer-friendly.
• Overall, Fusaka positions Ethereum to support a rapidly growing rollup-centric ecosystem without compromising decentralisation, while laying groundwork for a more private, resilient, and user-friendly network in the years ahead.

1. Introduction

The Fusaka upgrade, scheduled for mainnet activation on 3 December, represents Ethereum’s next major milestone following Pectra in May. While Pectra delivered user-facing improvements to the base layer - such as enabling EOA account code (EIP-7702) and increasing the validator maximum effective balance (EIP-7251) - Fusaka focuses on deeper infrastructural changes designed to reinforce L1 and L2 scalability to support Ethereum’s future growth. 

Despite the introduction of blobs in the 2024 Dencun upgrade and the expansion of blobspace in Pectra, blob demand on L2s is near its saturation levels, which can create upward pressure on fees. At the same time, L1 blockspace utilisation and gas pricing structures also require adjustments to better accommodate future scaling. 

Fusaka targets these dual challenges - L1 inefficiency and L2 blob bottlenecks - through a set of architectural upgrades aiming to improve throughput, reduce fees and enhance the overall user experience. This report outlines the Fusaka upgrade, its core EIPs and provides a forward-looking perspective on Ethereum’s Glamsterdam upgrade and privacy-focus framework. 

2. Overview of Fusaka Upgrade

Fusaka’s 13 EIPs can be grouped into three objectives: L2 scaling, improving L1 execution efficiency and improving user and developer experience. 

3. Impacts of Fusaka Upgrade

3.1 Increase L1 Throughput

Fusaka increases L1 throughput through a coordinated set of execution-layer EIPs that improves block composition, and eliminates execution and block propagation bottlenecks that previously limited scaling. These improvements enhance both the raw throughput (how much computational work fits into each block) and the effective throughput (how reliably the network can process that work at scale).

Below are four specific pathways through which Fusaka increases L1 throughput. 

Increase Gas Limit (EIP-7935)

Fusaka raises Ethereum’s default gas limit to 60 million units. A higher gas limit allows more computation and transactions per block, increasing L1 execution capacity. At the time of writing, around 47% of validators have a smaller than 45 million unit gas limit. After the EIP is implemented, Ethereum will have ~33% improvement in available block gas. 

Prevent Individual Transactions from Consuming Excessive Gas (EIP-7825)

Increasing block gas limits alone may not guarantee higher throughput if a single transaction consumes a large proportion of the block’s gas. EIP-7825 caps per-transaction gas at 16.8 million unit (Gwei) (2^24), which improves block composability, guarantees more transactions per block and allows for a more predictable throughput. It also lays the foundation for parallel transaction processing in the EVM. 

MODEXP Gas Repricing (EIP-7883)

Modular exponentiation precompile (MODEXP) is a function used in resource-intensive cryptographic operations such as RSA signatures and certain zero-knowledge proof systems. MODEXP transactions are often underpriced relative to its computational cost, which can put the network at risk when block capacity increases, as attackers can congest the network by packing many MODEXP-heavy operations. 

EIP-7883 fixes this by increasing the base cost and adjusts the cost multiplier to ensure MODEXP usage accurately reflects its computational requirements. This prevents transaction spam, contributes to a stable, predictable throughput for the Ethereum L1 and supports future gas limit increases.

Network Protocol Optimisation (EIP-7642)

EIP-7642 streamlines Ethereum’s P2P protocol by removing obsolete pre-merge fields and simplifying block messages. This can improve inefficiencies at the network layer, reduce bandwidth requirements, and prepare Ethereum for future execution improvements.

Collectively, these EIPs enhance Ethereum’s ability to process more transactions in one block space, handle surges in demand more smoothly and deliver a more reliable user experience.

3.2 L2 Scaling and Fee Reduction

Fusaka delivers meaningful economic and user experience improvements at the L2 level by directly addressing the fundamental bottlenecks that emerged after the Dencun upgrade - blobspace scarcity.

Blobs, introduced in Dencun (EIP-4844) in March 2024, became the primary mechanism to temporarily store large amounts of data, significantly reducing L2 transaction fees. However, demand for blobspace grew faster than the network’s initial capacity, which resulted in a blob capacity increase from a target/max of 3/6 to 6/9 during the Pectra upgrade. Since then, average blob usage has steadily climbed towards the new target.

As L2 rollup continues to expand, it becomes clear that continuously increasing blob limits through hardforks can be slow and insufficient. Additionally, scaling blobs via parameter increases raises the bandwidth and network requirements for validators, which may impact decentralisation especially for solo stakers.

In order to continue to support Ethereum’s rollup-centric roadmap, Ethereum needs to reliably scale L2s to accommodate rising throughput, while continuing to lower L2 fees.

PeerDAS (EIP-7594)

Peer Data Availability Sampling (PeerDAS) solves the architectural scaling limit. Currently, validators must download entire blobs to verify data availability (DA), which caps blobspace growth due to bandwidth and storage requirements. PeerDAS replaces full data download with a sampling-based approach using erasure coding - validators can verify data availability by sampling a small portion of the data (currently set at ⅛) while still confirming the full data is available across the network.  

This dramatically lowers per-validator load and allows the network to support larger blob limits without increasing hardware requirements. Ethereum’s L2 blob throughput can also be increased theoretically by up to 8x while preserving decentralisation guarantees. 

Blob-Parameter-Only (BPO) Hard Forks (EIP-7892)

BPO hardforks complement PeerDAS by enabling Ethereum to raise blob throughput quickly and predictably. Traditional hardforks, which require client-side logic changes and extensive testing, cannot respond quickly to fast-growing L2 demand. BPO hardforks modify only blob-related parameters (targets, limits and fee adjustment coefficients) without touching logic and execution rules. EIP‑7892 formalises a way to do small, frequent, blob-capacity-only hard forks, letting Ethereum scale its DA layer in stepwise, data-driven increments without waiting for full multi-feature network upgrades.

Fusaka has two scheduled BPO forks: 

• 17 December - increases blob target/max to 10/15
• 7 January - increases blob target/max to 14/21

These staged increases immediately expand L2 throughput and provide rollup teams with clear visibility into future capacity increases. 

Together, PeerDAS and BPO hardforks unlock L2 throughput gains by eliminating blobspace scarcity and reduce L2 transaction fees by lowering data-related gas costs. With more available blobspace, rollups can handle more transactions and avoid potential fee spikes during peak demand. This enables lower average fees but also a more stable fee environment, which improves user experience as L2 activity continues to accelerate.

4. Outlook

Glamsterdam

Looking ahead, the next major upgrade after Fusaka -  Glamsterdam, expected in the first half of 2026 - is poised to bring improvements to Ethereum’s censorship resistance, Maximum Extractable Value (MEV) transparency and user experience. 

Two headline EIPs currently under active development are EIP-7732 (Enshrined Proposer-Builder Separation, or ePBS) and EIP-7928 (Block-level Access Lists, or BALs). 

EIP-7732 aims to separate block proposals from block building to increase transparency of the block production process. This can reduce centralisation risks and enable more transparent MEV flows. On the other hand, EIP-7928 introduces  BALs, structured lists included by the block builder that specify all accounts and storage slots that transactions in the block will access or modify during execution. This enables parallel transactions, more efficient block construction and enhances execution-layer efficiency. 

Ethereum’s Privacy Roadmap

With the growing institutional and retail adoption, Ethereum also focuses on privacy because privacy is fundamental to user security and the broader adoption of decentralised applications on its network. Privacy protects users from surveillance, censorship, front-running, and data leakage, all of which can undermine trust and participation in Ethereum’s network, which aims to be the world's settlement layer. 

In 2025, the Ethereum Foundation changed the mission of its Privacy and Scaling Explorations (PSE) team as Privacy Stewards for Ethereum, and published a roadmap to bring privacy across Ethereum’s ecosystem. It announced an expanded focus on privacy through the formation of a Privacy Cluster, bringing together 47 researchers, engineers and cryptographers. 

Privacy Enhancements - Kohaku

At Devcon, Ethereum’s co-founder, Vitalik Buterin, further unveiled details on the initiative Kohaku, and described Ethereum as being on a “privacy upgrade path”. 

Kohaku is an open-source, privacy-focused framework designed to make privacy-preserving wallets and its software development kit (SDK) developer-friendly.  A core feature of Kohaku is the ability to create a stealth address using a user’s public key. This allows users to execute a private transaction without linking activities to their public wallet. Importantly, the real address can still be revealed for audits or regulations. This balances user privacy with regulatory and operational needs of real-world applications.

Kohaku’s roadmap also has several forward looking developments. This includes social recovery mechanisms using zero-knowledge proofs, use of Helios light client for browser-based execution and privacy-preserving account abstraction. Together, these initiatives aim to make privacy on Ethereum practical, secure, user-friendly and developer-friendly. 

5. Conclusion

The Fusaka upgrade represents a pivotal moment in Ethereum’s evolution. Through PeerDAS and the BPO hardforks, Fusaka unlocks an increase in L2 throughput and paves the way for Ethereum to react quickly to future scalability bottlenecks. It also improves the economics of user transactions and improves the predictability of blockchain performance. At the same time, Fusaka’s execution-layer refinements raise effective L1 throughput, ensuring Ethereum’s base layer remains robust to future upgrades.

Crucially, Fusaka lays the foundation for what comes next. Its scalability and stability improvements make it possible to safely introduce censorship resistant and privacy-enhancing features planned for Glamsterdam and Kohaku, respectively. With Fusaka in place, Ethereum becomes better equipped to support a rapidly growing rollup-centric ecosystem without compromising decentralisation, and also a more private, resilient and user-friendly network in the years ahead.

Read the full report: Ethereum Fusaka Upgrade

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Authors

Crypto.com Research and Insights team

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