Computer maker Lenovo Group Ltd. reached a proposed agreement to pay $8.3 million to end consumer class claims that the company installed ad software that created security vulnerabilities.

Starting in August 2014, Lenovo sold computers with pop-up ad software that created security vulnerabilities, according to the proposed settlement. The software could access sensitive consumer data, including Social Security numbers, medical information, and financial and payment information, according to the proposed settlement.

A Lenovo spokeswoman, Kristy Fair, told Bloomberg Law, “At...