Remember that Adobe security breach earlier this month that leaked the account records of some 3 million customers? Scratch that: the actual number hacked was at least 38 million, it has emerged.

In early October, Adobe warned of "sophisticated attacks" on its network in which hackers gained access to data for what was then believed to be about 2.9 million customers: that data included names, encrypted credit or debit card numbers, expiration dates, and other information relating to customer orders.

In addition, the company said, the cyber-crooks had managed to abscond with source code for "numerous Adobe products."

But in a blog post on Tuesday, investigative journalist Brian Krebs said those early estimates were far too low, and that the actual list of accounts that had been compromised numbered in the tens of millions.

How does Krebs know? Because he's seen the list. Over the weekend, he says, AnonNews.org posted a 3.8GB file called "users.tar.gz" that contained more than 150 million user and password pairs that had apparently been lifted from Adobe.

Adobe spokeswoman Heather Edell has since confirmed the breach to Krebs, adding that the company has contacted the owners of the affected accounts and has reset the passwords for all of the Adobe IDs that it believes were involved in the hacking incident.

"So far, our investigation has confirmed that the attackers obtained access to Adobe IDs and (what were at the time valid) encrypted passwords for approximately 38 million active users," Edell said. "We are still in the process of investigating the number of inactive, invalid and test accounts involved in the incident."

Edell also said that the attackers were able to gain access to at least some of the source code for Adobe Photoshop. Krebs was able to confirm that, too – a second, 2.56GB file posted to AnonNews.org contained what appeared to be Photoshop code.

Source code for Adobe Acrobat, Reader, and the ColdFusion web application server software is also believed to have leaked during the incident, but at least some of this data appears to have been password protected and may not be readily accessible.

Adobe seems to be taking its customer data breach seriously. The company has offered one year's worth of free credit monitoring by Experian to any customer whose account was compromised in the attack. But as Krebs points out, this kind of service isn't guaranteed to spot all of the forms of identity theft that might arise from such incidents, so Adobe customers are advised to place fraud alerts on their accounts and monitor their credit reports closely. ®