Tools can use a vBulletin forum account as a linked identity and as an additional sign-in method.
Open My Profile -> vBulletin / Forum at /me/vbulletin.
When your Tools email address is verified, Connect matching forum account searches for one exact vBulletin account with the same email address. If exactly one safe match exists, Tools stores the forum's stable user id on your Tools account. The profile flow does not require your forum password.
Tools refuses automatic linking when the email is unverified, no unique forum account matches, or the forum identity is already owned by another Tools account.
The normal login page keeps email/password and the existing Google sign-in option. SSO / other sign-in methods opens the additional provider chooser. When vBulletin SSO is enabled, choose vBulletin / Forum.
Tools redirects to the forum. An already authenticated forum member is returned with a short-lived signed identity assertion. Tools validates the signature, lifetime, audience and one-time login state before creating the Tools session.
If the forum identity is already linked, the mapped Tools account is used. A unique verified Tools email match may be linked automatically. If no Tools account exists, a Tools account may be created from the verified forum handoff. Ambiguous or conflicting identities are rejected.
The SSO handoff does not send forum passwords, password hashes, cookies or reusable forum session identifiers to Tools. Return destinations are restricted to local Tools paths, and failed identity/SSO operations are recorded through the platform audit and operational diagnostics systems without credential material.