Clipboard sync is a feature that copies clipboard contents from one device to another, such as moving text from a phone to a desktop. It is designed for convenience, but it also creates a new trust boundary: data that was meant to stay local can cross into another operating system, account, or enterprise environment.
In cyber security, this matters because clipboards often hold sensitive material such as passwords, one-time codes, API keys, internal notes, or personal data. If sync is enabled without clear controls, that content may become visible to another device, another user profile, or a compromised endpoint. Attackers may try to steal clipboard data through malware or session abuse, while defenders reduce risk by limiting sync, encrypting transfers, separating work and personal devices, and blocking clipboard use in higher-risk environments.