At least three China-based hacking teams have been exploiting a previously unknown flaw in Microsoft SharePoint since at least July 7, the company said in a blog post. Why it matters: Microsoft and security researchers didn't uncover the vulnerability until this past weekend,

At least 54 organizations have been breached in the attacks. Some of the attacks that targeted organizations using an exploit in Microsoft’s SharePoint server platform over the last few days have been linked to hacking groups affiliated with the Chinese government, according to a new Microsoft security blog.

Microsoft says Chinese hackers exploited security vulnerabilities in the company’s SharePoint platform, which it first reported over the weekend.