The game was billed as a huge clash in the League One relegation battle with two of the bottom-three sides going up against each other.
Shayne Lavery's first-half double was added to after the break by Dan Nlundulu and Elias Kachunga, with John Marquis' penalty proving scant consolation.
The victory lifts the U's to three points from safety, while Ainsworth's Shrews sit bottom and eight points adrift of the dotted line.
Ainsworth said: "Defensively, I can see now why the team is really struggling.
"We were very poor defensively today. Cambridge haven't ripped us apart with football, it's been basic stuff.
"Two throw-ins they've got in on, which is criminal. A free-kick, we're just not alive.
Diese Geschichte stammt aus der December 08, 2024-Ausgabe von The Football League Paper.
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Diese Geschichte stammt aus der December 08, 2024-Ausgabe von The Football League Paper.
Starten Sie Ihre 7-tägige kostenlose Testversion von Magzter GOLD, um auf Tausende kuratierte Premium-Storys sowie über 8.000 Zeitschriften und Zeitungen zuzugreifen.
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