Fidelity disclosed that the data of more than 77,000 customers was leaked in August and the relevant vulnerability has been fixed

According to ChainCatcher, Fidelity recently submitted a document to the Maine Attorney General stating that 77,099 of its customers were affected by the data breach, which is only a small part of its 51.5 million customer base.

It said an attacker gained access to customer names and other personal identifiers using two recently established customer accounts between August 17 and 19. The unauthorized access was terminated on August 19 when Fidelity first discovered the breach.

The company said it received assistance from "external security experts" to resolve the issue. Fidelity stressed that no third party had accessed any Fidelity accounts.

Fidelity said it would provide affected users with two years of free credit monitoring and identity restoration services "to detect any unusual activity that may affect a user's personal financial situation."