Formie: Unauthenticated users can overwrite incomplete submissions via submit action

Formie is a Craft CMS plugin for creating forms. Prior to 2.2.23 and 3.1.31, Formie's anonymous formie/submissions/submit action in SubmissionsController::actionSubmit trusts a client-supplied submissionId when loading an incomplete submission without session binding, ownership validation, or a valid submissionEditToken. An unauthenticated attacker can enumerate sequential IDs and overwrite or hijack another user's in-progress multi-page or save-for-later submission, and the modified data can be persisted and forwarded through notifications or integrations when the submission is completed. This is an incomplete remediation of CVE-2026-47266 because that earlier change validated edit tokens for save-submission but did not protect submit. Completed submissions are excluded by the isIncomplete filter. This issue is fixed in versions 2.2.23 and 3.1.31.