Microsoft Probing Whether Cyber Alert Tipped Off Chinese Hackers

Microsoft Corp. is investigating whether a leak from its early alert system for cybersecurity companies allowed Chinese hackers to exploit flaws in its SharePoint service before they were patched, according to people familiar with the matter.

The technology company is looking into whether the program — designed to give cybersecurity experts a chance to fix computer systems before the revelation of new security concerns — led to the widespread exploitation of vulnerabilities in its SharePoint software globally over the past several days, the people said, asking not to be identified discussing private matters.

“As part of our standard process, we’ll review this ...