ProseMirror's view component renders and manages the editable browser interface for ProseMirror documents. Prior to 1.42.3, prosemirror-view paste handling accepts attacker-provided HTML whose clipboard slice context contains attributes that are not passed through schema attribute validation. When a user pastes the crafted HTML into an editor, the unvalidated context attributes can construct content that executes attacker-controlled JavaScript in the browser window containing the editor. This issue is fixed in version 1.42.3.