Bridge risk is the security exposure that appears when value, data, or control moves between two connected systems, such as a blockchain bridge, sidechain, or cross-network payment rail. The bridge usually depends on special logic that locks, mints, validates, or redeems assets on each side. If that logic is flawed, the connected systems may disagree about what exists, who can move it, or whether transfers should be allowed.
This matters because bridges expand the attack surface: an attacker may target smart contracts, validators, custody keys, message relays, or pause controls instead of the underlying asset itself. In practice, bridge failures can lead to stolen funds, frozen redemptions, or tokens that cannot be safely converted back. Defenders reduce bridge risk with strong authentication, strict reserve accounting, limited privileges, independent audits, monitoring, and tested recovery procedures. In secure design, the bridge is not just a convenience layer; it is a critical trust boundary.