A guest user is a limited-access account or public-facing access context used in SaaS applications for sharing content, portals, forms, or support pages. In some configurations, a guest user may not require authentication at all, which makes it convenient for external visitors but also risky if permissions are too broad.
In cyber security, guest users matter because they can become an unintended data exposure path. If sharing rules, record-level permissions, or page components are misconfigured, a guest context may read sensitive records, enumerate objects, or export information without breaking a password. Attackers often look for these weak seams because they are low-noise and may blend into normal access. Defenders should minimize guest privileges, restrict visible fields and records, audit public pages and ACLs, and monitor for unusual read or export activity from low-trust contexts.