What problem does it solve? Cross-chain bridges and messaging protocols have lost billions to exploits like forged messages, replay attacks, and missing source validation. This Skill gives auditors a structured catalog of cross-chain vulnerability patterns with vulnerable and secure Solidity code examples, so they can systematically check contracts that send or receive cross-chain messages. ## Core Features & Use Cases - Vulnerability Pattern Library: Covers missing source chain/address validation, replay attacks, message ordering issues, chain-specific code assumptions (block.number, PUSH0), bridge lock/mint attacks, and finality assumptions. - LayerZero-Specific Checks: Provides the required validation sequence for lzReceive implementations, including endpoint, chain, and trusted remote verification. - Audit Checklist & Severity Classification: Ships a cross-chain audit checklist and Critical/High/Medium severity ratings to prioritize findings. - Use Case: While auditing a LayerZero-based token bridge, use this Skill to verify that lzReceive validates the endpoint, source chain ID, and trusted remote address, and that processed message IDs are tracked to prevent replay. ## Quick Start Audit this Solidity bridge contract for cross-chain vulnerabilities including missing source validation, replay protection, and finality assumptions.
