Kainat was injured when Taliban militants attempted to kill Malala at Mingora town in Swat on October 9.
The bomb attack this morning killed a woman and injured seven local residents.
Kainat and another girl, Shazia Ramzan, were injured in the attack on Malala. Both girls recently returned to school after recovering from bullet injuries.
Malala, who was shot in the head, is currently being treated at a hospital at Birmingham in Britain.
The Tehrik-e-Taliban Pakistan had claimed responsibility for the assassination attempt, saying Malala was targeted for backing secularism and Western values.
The Taliban have warned they will again target Malala and members of her family.