Zoom's Linux Client Silently Reads Every X11 Clipboard Copy

Simon Tatham, the developer behind PuTTY, reports that Zoom’s Linux client actively pulls the contents of the X11 clipboard every time anything is copied — not just when a user chooses to paste into Zoom. Under X11’s selection model, well-behaved applications register interest in clipboard ownership changes but only fetch the data when the user explicitly pastes. Zoom instead grabs the contents proactively the moment they change, meaning it sees clipboard data the user never intended to share with it.

The practical concern is privacy exposure. Anything copied while Zoom is running — passwords pulled from a manager, API keys, private messages, financial details — is read by the client regardless of whether a meeting or screen share is active. Because X11 places no meaningful isolation between applications’ clipboard access, users have no built-in defense and typically no indication that the snooping is happening.

The finding is a reminder that X11’s permissive clipboard design lets any running application eavesdrop on copy operations, and that a widely deployed proprietary app is exercising that capability far beyond what its function requires. It strengthens the case for Wayland, which restricts clipboard access, and for scrutinizing the local behavior of conferencing software that users tend to trust by default.