BNB Chain activates Pasteur hard fork to enhance bridge security

BNB intelligent chain main network activates Pasteur hard fork to strengthen the bridge verification and verifier rights mechanism

BNB intelligent chain has activated Pasteur hard fork on the main network and completed a series of protocol changes aimed at fixing loopholes in bridge verification and verifier authorization, while striving to package more transactions in each block. BNB Chain said in an announcement released on Tuesday that Pasteur is now online, integrates three BNB Evolution Proposals (BEP) and does not change the BSC's original 450-millisecond block time. This upgrade focuses on stricter cross-chain operation verifier management, more secure pledge and governance mechanisms, and the adoption of new block construction solutions during network congestion periods.

Core Points

Pasteur has been launched on the BNB intelligent chain main network, strengthening bridging verification and verifier authorization to reduce ambiguity in approval and voting.
BEP-682 prevents duplicate verifier entries during cross-chain light block verification and improves the correctness of bridge approvals.
BEP-695 strengthens protection of verifier key rotation, penalty mechanisms, and governance voting controls.
BEP-675 introduces a new block construction path that allows builders to submit blocks after executing transactions, while verifiers verify and sign before final execution of inspections.
BNB Chain reported that throughput increased by approximately 88% in QANet testing, while the average Gas fee per block increased-but the team emphasized that these were controlled test results, not main-network measured data.

Pasteur's changes to BSC main network

Pasteur integrates three protocol upgrades: BEP-682, BEP-695 and BEP-675, while solving security and performance bottlenecks. According to BNB Chain, BEP-682 is designed to prevent verifiers from being double counted during cross-chain light block verification, a change designed to make the bridging approval logic more robust. BEP-695 optimizes the security aspect of verifier lifecycle operations: it updates controls related to verifier key rotation, penalty mechanisms, and governance voting to ensure that old verifier privileges cannot be improperly reused. BNB Chain also stated that BEP-695 prevents restricted addresses from participating in voting, a targeted governance enhancement that reduces the possibility of unauthorized influence in the decision-making process.

The third component, BEP-675, changes the way block proposers and verifiers collaborate in transaction execution. The new path does not force verifiers to repeat work within a tight block window, but is designed to ensure that execution tasks are handled more efficiently without sacrificing consensus verification.

Why the new block construction path is important

Under BSC's original block construction method, the builder first executes the transaction and then submits the proposed block to the verifier. The verifier will execute the transaction again to confirm the content of the block before signing-BNB Chain said this work will consume the execution power of the BSC within the 450-millisecond block window. BNB Chain points out that when it is difficult to assemble blocks in such a short period of time, blocks may end up being underfilled during busy network times. Pasteur's changes are designed to reduce this waste.

BEP-675 allows builders to submit blocks they have completed execution. In this process, the verifier examines the proposed block according to consensus rules, then signs and broadcasts it. BNB Chain stated that the verifier then completed a comprehensive execution verification-separating consensus verification from final execution inspection to better adapt to the time constraints of BSC out-of-block production. Importantly, BNB Chain stated that the network does not force a single method: Builders can still use old paths, where verifiers perform transactions before signing, thereby enabling new paths when favorable while maintaining compatibility with existing operating practices.

Throughput improvements and higher block Gas fees in QANet testing

BNB Chain supports the performance motivation of BEP-675 through QANet internal testing. The team described QANet as a controlled environment designed to simulate the geographically distributed verifier settings of BSC. In these tests, BNB Chain reported that after building paths using updated blocks, throughput increased by approximately 88%, from 1237 transactions per second to 2324 transactions per second. At the same time, the average Gas fee per block increased from 46.35 million to 84.15 million. BNB Chain said that the block spacing and the 100 million Gas fee cap will remain unchanged. The network team warned that these results were obtained under controlled test conditions and were not direct main-network measured data. Still, this trend still has directional reference value for operators and developers: this upgrade is not only about shifting workload between builders and validators, but also about allowing blocks to carry more real transaction loads during peak demand periods.

Pasteur launches

Pasteur after BSC previously shortened block time is also part of a series of upgrades to BSC aimed at shortening block time and improving operational efficiency. Previous changes include the Maxwell hard fork, which BNB Chain said shortened the average block time from 1.5 seconds to approximately 0.8 seconds in June 2025. Subsequent Fermi upgrades further reduced the network out-of-block time to the current 450 milliseconds. With block intervals significantly reduced, the logic behind Pasteur's design becomes clearer: when blocks need to be produced quickly, redundant work on the verifier side can become a limiting factor. Pasteur's new builder to verifier execution handover mechanism is designed to ensure consensus verification is completed on time while still performing comprehensive execution inspections.

For investors and users, the practical significance is that chain expansion efforts are increasingly focusing on operational adaptation-maximizing utilization within a fixed block time-rather than changing core time parameters again.

What to focus on after the fork

With Pasteur now online, key issues for participants to focus on include how the BSC's validator set and block builders can adopt new paths under real-world network conditions, and whether observed test gains can translate into measurable improvements to the main network during peak hours. Equally important is monitoring whether bridge verification and governance participation are performing as expected under the new validator authorization and voting limits.