Flowise through 3.1.4 (Enterprise/platform mode with SSO enabled) contains an authentication bypass in the SSO login path. When an SSO callback arrives with an email matching a user whose status is INVITED, verifyAndLogin (SSOBase.ts:80-94) copies the user record from the database — including the server-stored single-use invitation tempToken — into the data passed to AccountService.register(). The register handler's token lookup, email match, and expiry checks therefore pass trivially against the server's own token instead of a caller-supplied one, and the account and its organization membership are flipped to ACTIVE. As a result, anyone able to authenticate at any configured SSO provider using a pending invitee's email address as the email claim can take over that invitation and obtain the invited user's access to the organization without ever possessing the emailed invitation token, for as long as the invitation is valid (24 hours by default). At the time of the advisory no patched version was available.