Hackers broke into the Washington Post Co's jobs website in two incidents last month, affecting more than a million user IDs and emails, the company said on its website.
The company said about 1.27 million users' IDs and email addresses were affected but no passwords or other personal information was accessed.
The company said the jobs accounts of users whose email addresses were accessed remained secure.
This latest breach comes amid a spate of hack attacks against high profile targets including Sony Corp and Citigroup.
Washington Post said it quickly identified the attack and took action to shut it down. It is pursuing the matter with law enforcement and conducting an audit of the security of its jobs site.
(Reporting by Abhishek Takle in Bangalore; Editing by)