Crosschain bridges have become a key solution to connect independent blockchains and enable the transfer of assets and information between them. However, recent bridge hacks have exposed severe security issues and these bridges provide new strategic weapons for malicious activities. Thus, it is crucial to fully understand and identify the security issues of crosschain bridges in the real world. To achieve our goal, we define a novel abstraction called \emph{inconsistency behavior} to comprehensively summarize the crosschain security issues. Then, we further developed XGuard, a static analyzer, to find the inconsistency behavior of cross-chain bridges in the real world. Specifically, XGuard first extracts the crosschain semantic information in the bridge contract on both the source chain and destination chain, and then identifies inconsistency behaviors that occur on multiple blockchains. Our results show that XGuard can successfully identify vulnerable crosschain bridges in the real world. The demonstration of the tool is available at https://youtu.be/UMASWldZHgg, the online service is available at https://xguard.sh, and the related code is available at https://github.com/seccross/xguard.