An XPath Constraint is a filter expression used in some application platforms to limit which database records a user can read, edit, or delete. In practice, it acts like a query guard: only objects matching the rule are returned or allowed through an access check. This makes it a core part of authorization design in data-driven apps.
In cyber security, XPath constraints matter because a small mistake can expose sensitive records or block legitimate access. Weak, missing, or overly broad constraints can let users reach data they should never see. Defenders use them to enforce least privilege, but they must also test how the runtime applies inheritance, special platform entities, and role settings. A constraint that looks strict in the model may still be ineffective if the underlying permission system behaves differently at runtime.