Bobby Robson's side turned in a hugely professional display in Bulgaria to take the upper hand in the tie and clinch their first win under their new manager. Nolberto Solano's brilliant 51st-minute free-kick set the Magpies on the way to their first win since 11 April, and Temuri Ketsbaia sealed it 13 minutes from time.
The game, only Robson's second in charge, was a triumph of teamwork and commitment and, although there were a few anxious moments in a hostile atmosphere, they were rarely in any trouble. Alain Goma and Nikos Dabizas were twin towers of strength in the United defence, while Rob Lee, discarded by the former manager Ruud Gullit, and Gary Speed were outstanding in the midfield engine room.
It was only Newcastle's fourth away win in Europe, and it could not have come at a better time after an appalling start to the season which has seen them take just one point from a possible 21 in the Premiership.
As expected, Robson reverted to his preferred 4-4-2 system for a game he desperately did not want to lose, with Warren Barton and Didier Domi filling the full-back berths and Goma and Dabizas again paired in the middle.
Newcastle had the first shot with five minutes gone when Alan Shearer tested the home goalkeeper, Nenad Lukic, from a tight angle, and the Magpies' captain showed some good early touches as he brought Solano and Domi into play on the flanks.
However, Robson's plans were thrown into turmoil with just 18 minutes gone when Duncan Ferguson, who had been in trouble for some time, was forced to hobble off, with Ketsbaia taking his place. But the change did not seem to hamper United and they almost took the lead within a minute as Gary Speed met Solano's free-kick and powered in a header which Lukic did well to turn on to the bar at full stretch.
The woodwork came to Newcastle's rescue after 25 minutes when Goma could only half-clear Rumen Hristov's corner and Milen Petkov blasted a first- time effort against the crossbar with the keeper Steve Harper well beaten.
Nine minutes before the break Speed found Domi on the left and he raced into the box before firing his effort into the side-netting. Six minutes after the interval, though, Newcastle took the lead.
Kieron Dyer was brought down by Sasa Mrkic as he weaved his way towards goal. Solano only had one thing in mind as he stood over the free-kick, and Lukic barely moved as the little Peruvian expertly curled his shot inside the keeper's right post.
The 200-strong band of travelling supporters, who had been largely drowned out by the home crowd, celebrated in fitting style as they sensed a turning point in the season, but they had to endure some tense few minutes as CSKA stepped up a gear in the search for an equaliser.
But, despite all their pressure, the Bulgarians were unable to create any serious chances and Solano almost claimed a second goal with a 75th- minute volley from Shearer's knock-down. It was left to Ketsbaia to finish things off two minutes later. Shearer sent Dyer away once again and the new England international slipped the ball to the Georgian, who turned past Galin Ivanov and lifted a shot over Lukic to make it 2-0.
"The players are learning and concentrating, and it is going much better," a happy Robson said. "We have played two away matches and we have conceded one goal - so that's a marked improvement. We conceded 18 goals in six matches prior to me coming here."
CSKA Sofia: Lukic; Kremenliev (G Ivanov, 61), Mrkic, Sarac, Velikov, Trenchev (Litera, 56), Chomakov, Petkov, Hristov (D Ivanov, 56), Berbatov, Manchev. Substitutes not used: Paskov (gk), I Ivanov, Kovacevic, Antonov.
Newcastle United: Harper; Barton, Dabizas, Goma, Domi, Solano (Hamilton, 82), Dyer, Lee, Speed, Shearer, Ferguson (Ketsbaia, 17). Substitutes not used: Karelse (gk), Robinson, Beharall, Hughes, McClen.
Referee: J Roca (Spain).