Yahoo said a major security breach in 2013 compromised all three billion accounts the company maintained, a three-fold increase over the estimate it disclosed previously.

The revelation, contained in an updated page about the 2013 hack , is the result of new information and the forensic analysis of an unnamed security consultant. Previously, Yahoo officials said about one billion accounts were compromised. With Yahoo maintaining roughly three billion accounts at the time, the 2013 hack would be among the biggest ever reported.

"We recently obtained additional information and, after analyzing it with the assistance of outside forensic experts, we have identified additional user accounts that were affected," Yahoo officials wrote in the update. "Based on an analysis of the information with the assistance of outside forensic experts, Yahoo has determined that all accounts that existed at the time of the August 2013 theft were likely affected."

The information taken in the heist may have included users' names, e-mail addresses, telephone numbers, dates of birth, passwords scrambled using the weak MD5 cryptographic hashing algorithm, and, in some cases, encrypted or unencrypted security questions and answers. Yahoo said investigators don't believe the stolen information included passwords in clear text, payment card data, or bank account information. Yahoo also provided updated figures in a press release and in a filing with the Securities and Exchange Commission.

Yahoo first disclosed the 2013 breach in December , with an estimate that it compromised one billion e-mail addresses. That hack is distinct from a separate intrusion Yahoo suffered in 2014 that the company said compromised 500 million accounts. Yahoo had disclosed it in September 2016 and said it was the work of state-sponsored hackers. In March, federal prosecutors charged two Russian intelligence agents with orchestrating the attack in a brazen campaign to access the e-mails of thousands of journalists, government officials, and technology company employees.

Yahoo left unchanged its estimates for a separate browser cookie-forging hack that took place in 2015 and 2016 and was carried out by the same state-sponsored attackers who participated in the 2014 breach. In its 2016 annual report, Yahoo said the forged cookies affected about 32 million accounts. There's no indication the 2013 breach and the cookie forging are connected or were carried out by the same attackers.

Besides the updated figure that all accounts were compromised in the earlier 2013 breach, the updated status page offered no new information. Still, the news is significant, in large part because it comes on the heels of a recently updated estimate from credit reporting service Equifax that a breach of its network exposed sensitive data for 145.5 million US consumers, up from a previous estimate that 143 million consumers were affected. Yahoo's previous one-billion account estimate already made the 2013 hack one of the biggest in terms of the number of people affected. The tripling of that estimate is sure to make it stand out even more.