Its existence is still to be confirmed by Adobe, but security researcher Mila Parkour from the Contagio Malware Dump blog seems to think it may be the real deal. According to her, the vulnerability is exploited via a malicious .pdf document sent as an attachment, and two files are dropped - and executed - on the system: nsunday.exe and nsunday.dll.
They are both components of a variant of Wisp - an information-stealing and downloader Trojan and, according to Softpedia, it is currently detected by 15 of the 42 AV solution used on VirusTotal.
If the flaw and its use in the wild is confirmed, Adobe will have to scramble to put out a patch way ahead of the selected date for the next security update. In the meantime, users could prevent becoming victims by disabling Flash support in Adobe Reader.
UPDATE: Apple has confirmed the existence of the vulnerability and plans to issue a patch for Flash Player around November 9 and patched up versions of Adobe Reader and Acrobat around November 15.