Ethereum security in 2026: What enterprises need to know now

The largest crypto theft in history—$1.5 billion from Bybit—wasn't a smart contract bug. It was a supply chain attack on wallet infrastructure. This single incident encapsulates the seismic shift in blockchain security heading into 2026: the threat landscape has evolved beyond Solidity vulnerabilities to target the entire operational stack, and enterprises processing significant transaction volume must adapt or face catastrophic losses.

The numbers are stark. Crypto hacks reached $3.4 billion in 2025, with North Korean state actors claiming $2.02 billion of that haul. Yet here's the counterintuitive insight: DeFi protocol losses actually declined relative to TVL growth, suggesting that mature security practices work—when implemented. The divergence between well-secured protocols and those suffering breaches has never been wider.

Access control failures now dominate the threat landscape

The OWASP Smart Contract Top 10 underwent significant revision in 2025, elevating access control vulnerabilities from fourth to first position—responsible for $953 million in losses last year alone. This reflects a fundamental shift: attackers increasingly target operational security rather than code logic.

The pattern is consistent across major incidents. WazirX lost $235 million when attackers compromised multisig signers through UI manipulation, displaying legitimate transactions while signing malicious payloads. The Bybit attack chain began with a compromised developer workstation, not a vulnerable contract. Eighty percent of stolen funds in 2024 came from off-chain attack vectors—compromised keys, phishing, and infrastructure breaches.

For enterprise security teams, this demands expanding the security perimeter. Pre-signing transaction simulations, large withdrawal time delays, and raw transaction validation are no longer optional. The traditional audit-once-deploy model is insufficient when the attack surface extends to CI/CD pipelines, custody infrastructure, and third-party wallet providers.

Pectra's EIP-7702 introduces critical new attack vectors

Ethereum's Pectra upgrade in May 2025 brought account abstraction closer to native protocol support—but security researchers identified serious vulnerabilities within months. EIP-7702 allows EOAs to temporarily delegate execution to smart contracts, enabling batch transactions and gas sponsorship. The tradeoff: over $12 million drained through EIP-7702-related phishing by August 2025.

Security firm GoPlus reports that 80-97% of observed EIP-7702 delegations were linked to malicious sweeper contracts. The attack is elegant: users approve delegation to what appears to be a legitimate DeFi interface, and automated bots drain remaining wallet balances.

More concerning for developers: EIP-7702 breaks longstanding security assumptions. Contracts relying on tx.origin == msg.sender checks are now vulnerable. The isContract() pattern for distinguishing EOAs from contracts is similarly compromised. Every protocol processing significant value should audit for these delegation-related vulnerabilities immediately.

The tooling renaissance changes the economics of security

The security tooling landscape has matured dramatically. Slither now exceeds 90 vulnerability detectors with a 10.9% false-positive rate. Aderyn, Cyfrin's Rust-based analyzer, delivers 100+ detectors with real-time IDE integration. Medusa v1.0, released February 2025, brings parallel fuzzing that scales linearly with hardware resources.

Most significant: Certora open-sourced its formal verification prover under GPLv3, democratizing mathematical proof-of-correctness for smart contracts. Combined with Certora's experimental AI Composer—which verifies AI-generated code against safety rules before execution—formal verification is transitioning from luxury to baseline requirement.

The practical DevSecOps pipeline now includes static analysis at commit (Slither + Aderyn), fuzzing in CI (Foundry + Medusa), and formal verification for critical paths (Certora). Protocols adopting this stack report 90%+ test coverage and dramatically reduced audit findings.

Multi-chain complexity creates enterprise risk

Cross-chain bridges remain the highest-value targets, with $2.8 billion stolen representing 40% of all Web3 hacks. The architecture is inherently risky: bridges concentrate liquidity while requiring complex validation across heterogeneous networks.

L2 security varies meaningfully. Arbitrum's multi-round interactive fraud proofs resolve disputes more gas-efficiently than Optimism's single-round on-chain verification. Block properties, timestamp behavior, and contract address aliasing all differ between chains—subtle variations that can introduce vulnerabilities when migrating audited mainnet contracts.

For enterprises operating across L2s, this demands chain-specific security reviews. A contract secure on Ethereum may exhibit unexpected behavior on Arbitrum due to different block number semantics or gas pricing. The 7-day challenge period standard across major optimistic rollups also creates capital efficiency tradeoffs that security teams must model.

Preparing for 2026: Where to focus

The regulatory environment is clarifying. MiCA and DORA in Europe, the GENIUS Act framework for stablecoins in the US, and evolving SEC guidance create compliance requirements that overlap significantly with security best practices. Ninety percent of hacked projects never had any form of audit; regulatory frameworks increasingly mandate them.

For 2026, enterprise security teams should prioritize three areas. First, operational security hygiene: key management, access controls, and infrastructure security now matter more than Solidity patterns. Second, EIP-7702 vulnerability assessment: any protocol accepting user transactions must audit for delegation-related attack vectors. Third, continuous monitoring: 70% of exploited contracts had audits but lacked post-deployment surveillance.

The threat actors are patient, well-resourced, and evolving. But the tooling, frameworks, and practices to counter them have never been more mature. The enterprises that adopt security-by-default culture—integrating formal verification, continuous fuzzing, and operational security into their development lifecycle—will define the difference between the protocols that thrive and those that appear on next year's Rekt leaderboard.