When a penetration tester discovers a significant vulnerability such as a web component that allows file uploads without any authentication requirements, it poses an immediate and severe security risk. Notifying the primary contact immediately is critical to ensure that the organization is aware of the vulnerability and can take swift action to mitigate the risk. This approach prioritizes the security of the organization's systems and data, and it allows the appropriate personnel to assess the situation and decide on the best course of action, such as temporary remediation or further investigation.