The Washington, D.C., newspaper reported Tuesday that it had found evidence of a massive breach in an internal system that allows bloggers to upload and manage their own posts.
The breach was first reported in August by Wired magazine, which said it uncovered the data in July.
The Post reported that it was working with several law enforcement agencies to determine who was responsible for the breach.
It said that an anonymous tip led authorities to a computer that had been compromised in August.
The paper did not identify the hackers who had accessed the computer.
It also did not say how many posts had been exposed.
“The Post’s research into the matter suggests the attack is likely of significant scale and may include more than 1 million blog posts,” the newspaper wrote.
The Washington Examiner, which first reported on the story, wrote that “this particular data breach was the largest ever uncovered by a news outlet.”
The paper said that it discovered the breach in early August.
It noted that it would release additional details about the breach at a later date.
The data breach is the latest in a string of security breaches that have affected media organizations.
The Associated Press reported last month that its newsroom had been hit by a ransomware attack, which infected journalists’ computers and then demanded payment in Bitcoin.
That attack was traced back to a Romanian hacker known as “Troy.”
The AP said the ransomware was not the only breach that affected the AP’s network, with others also reported by the Los Angeles Times and the New York Times.
The AP reported that its computer network had been hacked earlier this month, but said it did not know who was behind the attack.