Base ZK upgrade implementation: optimistic proofs come to an end, Ethereum L2 security enters the zero-knowledge verification era

May 4, 2026, Ethereum Layer 2 network Base announced a major upgrade industry insiders are calling the “L2 Security Watershed.” By partnering with zero-knowledge proof infrastructure company Succinct Labs, Base integrated the SP1 zero-knowledge virtual machine into its Azul upgrade, introducing cryptographic-level finality confirmation for approximately $7.4 billion in deposits on the network. This not only means that the withdrawal wait time for users moving funds from Base back to the Ethereum mainnet will be significantly reduced from up to 7 days to 1 day, but also marks a structural shift in the security standards of the Ethereum L2 ecosystem—from “game-theoretic trust” to “mathematical verification.”

With the mainnet activation date set for May 13, this event is sparking widespread discussion about Ethereum L2 security models, proof architecture, and decentralization pathways.

Key Facts at a Glance

Security Upgrade for $7.4 Billion in Assets

On May 4, Base officially announced that it will introduce the SP1 zero-knowledge virtual machine developed by Succinct Labs through the Azul upgrade, used for generating zero-knowledge proofs. The core of this collaboration is that SP1 will prove approximately $7.4 billion in deposits on Base, making this network the largest single Ethereum operator to date to adopt ZK proofs for finality.

Wilson Cussak, head of the Base network, stated: “As the network scales, the demand for strengthening the infrastructure relied upon by users and developers is also growing. Extending Base with ZK proofs is an important step in deepening network security and resilience.”

It’s noteworthy that Base has not completely abandoned its existing optimistic rollup architecture but has chosen a hybrid approach—combining TEE proofs with ZK proofs within a multi-proof system. The Azul upgrade went live on the testnet on April 21, and the mainnet will be officially activated on May 13. To ensure code security, Base launched an audit contest on the Immunefi platform, with a total prize pool of $175,000 base pool and $25,000 all-star pool. The contest started on April 21 and ends on May 4.

Transition from OP Stack Dependency to Independent ZK Architecture

Base’s ZK transition is not an isolated decision but a continuation of a series of technical and strategic adjustments. Understanding this process helps position this upgrade within the broader development trajectory of Base.

2024 to 2025: OP Stack Era

Initially launched as a member of the Optimism Superchain ecosystem, Base used OP Stack as its underlying technology framework. Under this architecture, Base adopted an optimistic rollup model—assuming all transaction batches are valid by default, with a challenge period of about 7 days during which anyone can dispute suspicious transactions. This model’s security relies on the “wait for dispute” assumption.

February 2026: Moving away from OP Stack to a unified codebase

Base announced it would detach key network components from OP Stack and integrate them into its own unified codebase. From then on, node operators would track Base’s own release versions rather than those of Optimism, increasing network upgrade frequency from three times a year to six. Additionally, Base announced plans to shift from optimistic proofs to a TEE/ZK proof architecture in subsequent hard forks, maintaining Stage 1 rollup status and adding independent signers to the security council.

April 21, 2026: Azul upgrade launches on testnet

Azul upgrade was officially deployed on the testnet, introducing a multi-proof system—combining TEE and ZK proofs. The new architecture unified Base’s client stack into a single base-reth-node execution client and a Kona-based new consensus client, base-consensus. After the upgrade, the number of empty blocks dropped from about 200 per day to around 2, a 99% reduction; the network handled multiple bursts of 5,000 TPS during testing.

May 4, 2026: ZK proof partnership officially announced

Base and Succinct’s collaboration was publicly announced, with SP1 used to prove approximately $7.4 billion in deposits on Base.

Expected May 13, 2026: Mainnet activation

Azul upgrade will be officially activated on Base’s mainnet, marking the entry of the hybrid multi-proof system into production.

Timeline Overview

How Multi-Proof Systems Reshape L2 Security Models

Flaws in the Old Architecture’s Security Assumptions

Under the optimistic rollup model, Base assumes all submitted state batches to Ethereum mainnet are valid. Only if someone submits a fraud proof within the 7-day challenge window does the system review disputed transactions. The security core of this mechanism relies on two premises: first, that at least one honest validator is willing and able to discover and submit fraud proofs within the specified time; second, that the challenge period is long enough to cover the validator’s discovery and response time.

In reality, the friction lies in the fact that the 7-day lock-up period limits capital efficiency. Additionally, the security effectiveness of the challenge period has a nonlinear relationship with network scale: as assets grow and transactions become more complex, the validation pressure during a single challenge window increases.

New Architecture: TEE + ZK Dual Verification

The core design of the Azul upgrade is to build a multi-proof system that runs two independent verification channels:

TEE proof channel: generated by a Trusted Execution Environment, a permissioned channel with high processing efficiency. TEE provides hardware-level isolation, ensuring the computation process is tamper-proof.

ZK proof channel: generated by SP1 zero-knowledge virtual machine, a permissionless channel. SP1 supports writing verification programs in standard Rust, compiling to RISC-V, and generating ZK proofs for execution. Developers do not need to write custom circuits for ZK integration.

Both proofs can independently finalize transaction proposals. When both results agree, withdrawal settlement time is reduced from 7 days to 1 day. When the two proofs conflict, the permissionless ZK proof will override the TEE proof—this design provides on-chain fault detection and handling, marking a key step toward L2BEAT’s Stage 2 decentralization definition.

SP1’s Performance Foundation

SP1 has verified metrics such as: under a 16 RTX 5090 GPU configuration, SP1 Hypercube can generate Ethereum mainnet 99.7% block proofs within 12 seconds. It is also the first zkVM to fully formalize-verify all 62 RISC-V core opcodes, a task completed jointly by Nethermind Security and the Ethereum Foundation.

From an ecosystem adoption perspective, SP1 has generated millions of proofs for over 35 clients, covering protocols like Polygon, Mantle, and Lido, with total assets covered around $4 billion.

Architecture Comparison

Public Opinion Breakdown: Is ZK the Endgame or a Transition?

The introduction of ZK proofs on Base has sparked multi-layered discussions within and outside the industry. The following summarizes based on public statements, community debates, and technical analyses.

Supporters: ZK is the Inevitable Future of L2 Security

Brian Trunzo, Chief Growth Officer at Succinct Labs, described Base’s decision as “ZK proofs being the biggest trust vote for Ethereum’s ultimate scaling form,” seeing this as a sign that the market is beginning to view ZK as the strategic direction for scaling ecosystems.

Ethereum co-founder Vitalik Buterin has repeatedly described ZK-EVM as Ethereum’s “final” block validation system, expecting such systems to become mainstream between 2027 and 2030. Base’s upgrade aligns with Buterin’s timeline.

From a technical community perspective, optimistic rollups rely on economic incentives and honest participation assumptions, while ZK proofs replace these trust assumptions with mathematical certainty. Several security researchers have pointed out that as L2 asset scales grow, purely game-theoretic security models will face diminishing returns—attackers’ gains increase with TVL, but defenders’ incentives do not grow linearly.

Cautious View: Hybrid Architecture Risks

Not all industry participants fully endorse Base’s approach. Some technical analyses highlight that Azul’s multi-proof system introduces TEE reliance—TEE is essentially a trust assumption on hardware manufacturers, which conflicts with core decentralization principles. If TEE is compromised, the verification logic depending on it could be affected.

Furthermore, the cost of generating ZK proofs is a tangible constraint. Unlike optimistic rollups, which do not compute proofs unless challenged, ZK proofs require cryptographic computation at each submission. With Ethereum L2 fees already very low, who bears this incremental cost and whether it impacts transaction fees remains an open question.

Community Perspective: Security Upgrades and Governance Controversies

A notable background is that Base recently faced community scrutiny over how it gained asset attention. Some users questioned whether certain projects had behind-the-scenes support. Jesse Pollak, co-founder of Base, publicly responded that the team would never engage in price manipulation or covert coordination to promote specific assets, noting such actions could cross legal boundaries. While this controversy is not directly related to the ZK upgrade, it adds a layer of external skepticism about Base’s security upgrade narrative—when governance transparency is questioned, trust signals from technical upgrades may be somewhat diluted.

Opinion Distribution Summary

Industry Impact Analysis: L2 Security Standards Are Being Rewritten

Structural Impact on L2 Competition

The industry impact of this upgrade should not be viewed solely as a technical iteration of a single network but as a paradigm shift in L2 security standards.

First, it establishes a new reference point for L2 security upgrades. Prior to Base, some L2s had begun exploring ZK proof integration—for example, Linea reduced proof generation time from about 30 minutes to roughly 60 seconds; Optimism has included validity proofs in its roadmap and established a strategic partnership with Succinct in February 2026. But Base, with its largest TVL and proof coverage of $7.4 billion, pushes ZK verification into an unprecedented asset scale. This effectively sets an implicit security benchmark for the entire L2 industry: when the largest secondary network adopts ZK proofs as a core security component, other networks maintaining purely optimistic security narratives will face increasing interpretive costs.

Second, accelerates the trend of integrating optimistic and ZK proofs. The L2 industry is experiencing a shift from a binary “optimistic vs ZK” route choice to a more integrated “hybrid” architecture. Emerging L2s like RISE have adopted combined fraud proof systems. Base’s choice will further accelerate this convergence.

Third, objectively promotes the decentralization process of L2. L2BEAT’s decentralization rating framework defines Stage 2 as “completely trustless”—requiring on-chain fault detection capabilities and sufficiently long exit windows. The ZK proof design in Base’s Azul upgrade can cover TEE faults, directly addressing the “on-chain detection of system errors” requirement for Stage 2. Although Base is currently still in Stage 1, this upgrade provides a technical foundation for its progression toward Stage 2.

Impact on Ethereum L1 and L2 Relationship

Base’s ZK upgrade also occurs against the broader background of evolving relationships between Ethereum mainnet and L2s. Currently, total L2 TVL is around $32.3 billion to $43 billion. As L2 security standards shift toward ZK proofs, the governance and security infrastructure of L2s will become more complex, and the boundary of responsibilities between L1 and L2 will be redrawn. The Ethereum research community is discussing proposals like EIP-8025 and native proof verification, aiming to generalize L1 consensus layer proof verification infrastructure into a program-agnostic universal layer, which could fundamentally change the design paradigm of L2 security architecture.

Conclusion

By introducing SP1 zero-knowledge proofs through the Azul upgrade, Base has technically transitioned from a single optimistic proof system to a hybrid multi-proof architecture combining TEE and ZK proofs; industry-wide, it sets a reference for the evolution of security standards in Ethereum’s L2 ecosystem. The cryptographic protection of $7.4 billion in deposits, the efficiency leap reducing withdrawal times from 7 days to 1 day, and the redundancy design where ZK can cover TEE faults—all point to a clear trend: the security foundation of Ethereum L2 is shifting from “game trust” to “mathematical verification.”

However, this shift is not the end. Reliance on TEE trust assumptions, the computational costs of ZK proofs, and long-term performance in real mainnet environments still require ongoing observation and testing in future market cycles. L2 security is not achieved in a single moment but is gradually approached through countless architecture choices, lessons from failures, and continuous iteration. Base’s move brings the entire industry a step closer to that ideal state.