Twitter, Tumblr and Pinterest have been caught up in a hacking attack on a firm, which technology companies use to outsource their customer services.
Customer support tool Zendesk noted that a hacker downloaded email addresses of users who contacted those three customers for support, along with the email subject lines.
The company warned customers of the security breach in an email entitled: "We've been hacked."
According to the website Wired.com, some customers also may have had their phone numbers revealed, but no passwords were revealed.
Zendesk, which has over 25,000 clients, uses software tools to allow companies to outsource a number of their customer service functions.
In an email to affected users, Twitter wrote: "Zendesk's breach did not result in the exposure of information such as Twitter account passwords. It may, however, have included contact information you provided when submitting a support request such as an email, phone number, or Twitter username."
According to the paper, Pinterest and Tumblr sent similar emails warning their potentially affected users. (ANI)