He's been working on it for months, and according to a later post, he has now a working exploit that "grants SYSTEM on all currently supported versions of Windows."
According to Computerworld's Gregg Keizer, Microsoft has confirmed that they have been mare aware of the issue, and are currently investigating it. Luckily, it is not being exploited in the wild as of yet.
According to Secunia, it is a potential privilege escalation vulnerability that could also be used to execute arbitrary code on the target system or DoS it, and affects fully patched Windows 7 and reportedly also Windows 8, but can be taken advantage of only by attackers that have physical access to the machine.
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