BNB Chain is preparing to activate its Pasteur hardfork on BNB Smart Chain mainnet at 02:30 UTC on August 25, introducing security changes around cross-chain verification and validator management alongside a new block-building path designed to increase capacity. All BSC mainnet nodes must be running client version 1.7.7 before activation, making the release mandatory for infrastructure operators.
The upgrade follows Pasteur’s July 21 deployment on the BSC testnet. In its official Pasteur announcement, BNB Chain identifies BEP-682 and BEP-695 as the changes requiring the hardfork, while BEP-675 is enabled around the Pasteur rollout through a separate RPC-controlled path. The distinction matters because Pasteur combines consensus-level security hardening with a capacity improvement that does not itself alter consensus rules.
Pasteur Tightens Bridge and Validator Security
BEP-682 strengthens BSC’s cross-chain light-block verification by rejecting duplicate validators inside submitted validator sets. Before the change, a crafted set could theoretically repeat validator identities and inflate apparent voting power. Pasteur closes that verification gap by enforcing uniqueness across validator addresses, consensus keys, BLS keys and relayer addresses before bridge validation proceeds.
BEP-695 addresses a separate group of staking and governance weaknesses related to validator key rotation. Old consensus keys will lose administrative authority after rotation, pending slash eviction will follow validators to their new keys, and blacklisted addresses will be rejected when governance votes are submitted through signature-based methods. The changes are designed to prevent retired credentials or incomplete blacklist checks from retaining privileges they should no longer possess.
BEP-675 Targets Fuller Blocks Without Faster Block Times
The capacity component comes from BEP-675, which removes redundant transaction execution from the critical builder-to-validator path. Builders can submit blocks they have already executed, allowing validators to perform consensus checks, seal and broadcast them before completing full local verification. The goal is to give builders more of BSC’s existing 450-millisecond block window to fill blocks rather than spending that time repeating execution work.
BNB Chain reported that controlled QANet testing increased throughput from 1,237 to 2,324 transactions per second while keeping the 450ms block interval, 100 million gas limit and finality lag unchanged. Those figures represent test-environment results, not guaranteed mainnet performance, so the practical capacity gain will need to be measured after deployment.
For ordinary users and most dApp developers, Pasteur requires no migration or asset movement. Node operators, however, need to replace their binary and remove [Eth] EnableBAL from config.toml, because leaving that field in place will prevent the updated client from starting. The official BSC v1.7.7 release record confirms the mandatory upgrade and activation schedule. Nodes that remain incompatible after the fork risk falling out of sync with BSC mainnet, making operator readiness the immediate priority ahead of August 25.