Tech giant Microsoft warned some of its Azure cloud computing customers that a flaw unravelled by security researchers could have allowed hackers access to their data.
In a blog post from its security response team, Microsoft said it had fixed the flaw reported by Palo Alto Networks and it had no evidence malicious hackers had abused the technique.
It said it had notified some customers they should change their login credentials as a precaution.
The blog post followed questions about the technique described by Palo Alto. Microsoft did not answer any of the questions, including whether it was confident no data had been accessed.
In an earlier interview, Palo Alto researcher Ariel Zelivansky told his team had been able to break out of Azure`s widely used system for so-called containers that store programs for users.
The Azure containers used code that had not been updated to patch a known vulnerability, he said.
As a result the Palo Alto team was able to eventually get full control of a cluster that included containers from other users.
Palo Alto reported the issue to Microsoft in July. Zelivansky said the effort had taken his team several months and he agreed that malicious hackers probably had not used a similar method in real attacks.
Still, the report is the second major flaw revealed in Microsoft`s core Azure system in as many weeks.
In late August, security experts at Wiz described a database flaw that also would have allowed one customer to alter another`s data.