All users of an online note-taking app are being forced to change their password after “suspicious activity” was discovered on the company’s network.
The firm said an attempt had been made to access secure areas of its service, where subscribers keep everything from written notes to photographs and voice memos.
But it added that no content stored on the service had been accessed, changed or lost.
“As a precaution to protect your data, we have decided to implement a password reset,” users were told in a statement.
“The investigation has shown that the individual(s) responsible were able to gain access to Evernote user information, which includes usernames, email addresses associated with Evernote accounts and encrypted passwords.
“Even though this information was accessed, the passwords stored by Evernote are protected by one-way encryption.”
The company said its decision to force users to change their passwords was the result of an “abundance of caution”.
It added: “As recent events with other large services have demonstrated, this type of activity is becoming more common.
“We take our responsibility to keep your data safe very seriously, and we’re constantly enhancing the security of our service infrastructure to protect Evernote and your content.”
Microsoft, Apple, Twitter and Facebook have all been targets of hackers recently.
There were also high-profile attacks at The New York Times, The Washington Post, and the Wall Street Journal.
They prompted President Obama to sign an executive order on cybersecurity.