why not:
UPDATE a
SET a.Status = 'INVALID'
FROM CandidateTable a
JOIN CriteriaTable b
ON b.CampaignID = a.CampaignID AND b.CriteriaTypeID = 1 -- same as the WHERE EXISTS clause
WHERE NOT EXISTS (SELECT 1 FROM CriteriaTable b WHERE b.CampaignID = a.CampaignID AND b.CriteriaTypeID = 1 AND b.Criteria = a.Criteria)
Gerald Britton, Pluralsight courses