[Update 8.38am GMT: LastPass statement]
A dangerous, previously unknown security vulnerability has been discovered in LastPass which permits attackers to remotely compromise user accounts.
LastPass is a password vault which pulls user passwords from a secure area and auto fills credentials for you. The system uses AES-256 bit encryption with PBKDF2 SHA-256 and salted hashes to protect the valuable data stored within, but according to Google Project Zero hacker Tavis Ormandy, the software contains a "bunch of critical problems" which could put user accounts at risk.
On Tuesday, the white hat researcher revealed on Twitter that he was exploring LastPass security, claiming that it only took a "quick look" to find "obvious" security problems.
According to The Register, millions of users may be at risk until the problem is patched -- and it only takes a visit to a malicious website to become a victim. If an attacker is able to compromise a LastPass account, this gives them access to a treasure trove of credentials for other online services.
Ormandy has sent a report detailing the zero-day and any other critical security issues the researcher found. However, no technical details have been released or are likely to be until LastPass has replicated Ormandy's findings and patched any problems.
The researcher, who has found critical problems and security failures in software including Symantec products and Avast solutions is setting his sights on 1Password next.
LastPass said in a blog post:
"An attacker would need to successfully lure a LastPass user to a malicious website. Once there, Ormandy demonstrated that the website could then execute LastPass actions in the background without the user's knowledge, such as deleting items. As noted below, this issue has been fully addressed and an update with a fix was pushed for all Firefox users using LastPass 4.0."