The chief executive of the pipeline operator that was temporarily crippled by a ransomware attack last month apologized to Americans. During testimony before a Senate panel on Tuesday, he acknowledged that Colonial Pipeline was susceptible to hackers and that it is still grappling with challenges caused by the infiltration.

“We are deeply sorry for the impact that this attack had,” CEO Joseph Blount Jr. said.

Fielding questions from members of the Senate Homeland Security and Governmental Affairs Committee, Blount addressed concerns about the company’s cybersecurity practices and its decision to pay the hackers a hefty seven-figure ransom.

The appearance was Blount’s first before Congress since the May 7 ransomware attack that forced the Georgia-based pipeline...