NATO's International Security Assistance Force said Forward Operating Base Fenty in Nangarhar province was attacked by three "vehicle-borne suicide bombs" before 6 a.m., but the attackers didn't manage to breach the base perimeter.
A police spokesman told CNN at least 14 Afghan soldiers and four civilians were wounded by the explosions.
Additionally, the three suicide bombers and six gunmen were killed, the spokesman said.
NATO helicopter gunships from the nearby Jalalabad Airfield were deployed to repel the gunmen who followed the bomb vehicles, the BBC said.
The base is in a region NATO turned over to Afghan security forces this year. It was last attacked in April. In February, nine people at the base were killed by a Taliban attack.