Not so with Microsoft in the case of Windows 8 RTM, or "release to manufacturing," the Aug. 1 milestone that gave the go-ahead for computer makers to start preparing new PCs and for some customers to download, install and start using the upgrade.

Last month, Adobe issued two updates for Flash Player that patched eight vulnerabilities, some of which were ranked as "1" by the company, its highest threat warning. One of the vulnerabilities, tagged as CVE-2012-1535, was patched Aug. 14, but had been exploited for an indeterminate time before that.

In fact, CVE-2012-1535 was one of four "zero-days," or unpatched vulnerabilities, exploited in a 16-week stretch by an revealed by Symantec researchers on Friday.

Microsoft has not updated the Flash in IE10 within Windows 8 to accommodate those two sets of patches, Adobe confirmed Friday. "Flash Player 11.3.372.94 does not incorporate the fixes released in APSB12-18 and APSB12-19," said Wiebke Lips, a spokeswoman for Adobe, referring to the Aug. 14 and Aug. 21 Flash updates.

Windows 8 RTM's IE10 identifies the integrated Flash Player as version 11.3.372.94, a more recent build than the one in Windows 8 Release Preview, but older than the most-up-to-date version for Windows, 11.4.402.265, which Adobe delivered on Aug. 21.