Gas Optimization Audit: Polygon Bridge
Gas Optimization Audit: Polygon Bridge Target Protocol : Polygon Bridge (TVL: $2766.2M) Polygon Bridge – Gas‑Optimization Audit Protocol: Polygon Bridge (Ethereum ↔ Polygon PoS) TVL (approx.): $2.766 B (Ethereum + Polygon) Audit Type: Gas‑Efficiency Review (with security‑impact considerations) Date: 10 Oct 2026 Auditor: Senior DeFi Security Researcher – [Your Name] 1. Executive Summary The…
A senior DeFi security researcher conducted a gas‑efficiency review of the Polygon Bridge on October 10, 2026, focusing on the contract pathways handling $2.7 billion of value. The bridge, moving ERC‑20, ERC‑721, and ERC‑1155 assets between Ethereum and Polygon, experienced several gas‑heavy patterns that could increase user fees and network congestion.
The audit identified five attack vectors:
1. A1: Unbounded Loop on Large Deposit Sets could deny service to depositors by submitting batches with tens of thousands of token IDs.
2. A2: Gas‑Griefing via bytes Decoding could enable griefing attacks on exit functions via malformed data in ERC1155 predicates.
3. A3: State Sync Over‑writes (Replay) through unchecked nonce increments in the StateSync contract, which could allow double‑spend or asset duplication.
4. A4: Excessive Storage Writes in withdraw due to writing the same processedExits flag multiple times per transaction, inflating gas costs.
5. A5: Inefficient ERC20 transferFrom checks that could enable a gas‑grief scenario for batch withdrawals.
The audit recommended prioritizing technical recommendations to improve gas efficiency, including introducing a hard‑cap on batch sizes, caching bytes length and using assembly for decoding, removing unnecessary counter increments with unchecked blocks, consolidating flag writes, pre‑checking ERC20 allowances, adding overflow guards for nonces, and deploying a Gas‑Refund helper contract for batch withdrawals.
Implementing these optimizations could reduce average transaction costs by 15‑30% and mitigate potential attack vectors.
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