NEW YORK — Best Buy, TiVo and Walgreen are the latest in a seemingly endless string of companies to warn over the weekend that hackers gained access to customers’ files, including e-mail addresses.

The companies all use the same marketing and communications vendor, Epsilon. It’s a leading marketing services firm that sends more than 40 billion e-mails annually and has more than 2,500 clients including seven of the Fortune 10. Epsilon, based in Dallas, issued a brief statement on Friday saying “a full investigation was under way” following the discovery of the breach of some customer client data. The company said that information obtained was limited to names and e-mail addresses and that “no other personal identifiable information associated with the names was at risk.”

The companies affected said Epsilon informed them of the breach and told them the compromised files do not include any personally identifiable information stored with the marketer. However, hackers could use these e-mail addresses to trick customers into providing more personal information such as Social Security numbers.