Sommer denied Maccabi Tel-Aviv striker Eran Zahavi 18 minutes from time as a tight contest ended goalless.
The home side started the better and finished strongly, but were unable to make their periods of pressure count to leave the tie in the balance ahead of next week's second leg.
Maccabi began in positive mood with both midfielder Maharan Radi and striker Barach Yitzhaki having good chances on goal inside the opening six minutes, with the latter forcing a save from Sommer.
However the Swiss side, who started their European campaign in the Champions League in the same group as Chelsea and Schalke, rallied and after Philipp Degen had headed wide, fellow defender Gaston Sauro tested goalkeeper Juan Pablo Colinas with a 20th-minute effort.
But as the break approached, it was Maccabi frontman Zahavi who came closest to breaking the deadlock with a 38th-minute shot which flew wide.
Basle returned in determined fashion in the second half and Serey Die saw a 55th-minute audacious effort blocked seconds before fellow midfielder Taulant Xhaka had just fired wide.
But Maccabi's Omri Ben Haroush tested Sommer with 28 minutes remaining, and the goalkeeper was on hand again 10 minutes later to keep out Zahavi's attempt.
Radi had an 83rd-minute shot blocked with the home team desperate to take a lead into next week's second leg, but Colinas had to keep out substitute Valentin Stocker's effort at the death to secure a draw.