Oxford atoned for their humiliating 44-0 defeat 12 months ago with victory in a fiercely-competitive 27th PCubed Varsity match at the Twickenham Stoop.
Looking for a third successive win, Cambridge made the best possible start with a second-minute try from lively hooker Kelvin Donald from close range, and stand-off Dave Bulley went 70 metres for a second on 12 minutes.
But Bulley was wide with both conversion attempts, whereas Oxford full-back Andrew Cook succeeded with all four of his attempts at goal.
A surging run from Cook set up a try for centre Andrew Benger while a break by scrum-half Duncan Knox created one for impressive winger Dave Black as the Light Blues led 14-8 at half-time.
Cambridge centre Matt Bray forced his way over from close range on the hour and Bulley Like