The McAfee blog carried details of the bug on Friday.
Thereafter, FireEye posted details itself on 8 April, saying: "FireEye shared the details of the vulnerability with Microsoft and has been co-ordinating for several weeks public disclosure timed with the release of a patch by Microsoft to address the vulnerability.
"After recent public disclosure by another company, this blog serves to acknowledge FireEye’s awareness and coverage of these attacks."
FireEye said: "In both observed documents the malicious script terminated the winword.exe process, downloaded additional payload(s), and loaded a decoy document for the user to see. The original winword.exe process is terminated in order to hide a user prompt generated by the OLE2link."
McAfee said in its post of 7 April that "the samples we have detected are organised as Word files (more specially, RTF files with '.doc' extension name).
"The exploit works on all Microsoft Office versions, including the latest Office 2016 running on Windows 10. The earliest attack we have seen dates to late January."
As can be seen from the screenshot embedded above, the Intel-owned McAfee''s blog post requires privacy protection to be disabled in order that a user can read the Web page.
Microsoft is due to release its next batch of security updates on Tuesday, 11 April, US time.