Is already being actively exploited by criminals.
Adobe has been made aware of the existence of a vulnerability in its PDF products, and Acrobat Reader, which is already being exploited by malicious.
According to the security firm Secunia the vulnerability is due to an error in font-analysis in CoolType.dll library to the Windows version of the software, but Adobe says that the vulnerability is not operating system dependent. This is apparent in all versions of Adobe Reader and Acrobat to version 9.3.4 and earlier.
Using a specially crafted PDF file occurs a stack based buffer overflow bugs that get the software to crash, which could give the attacker full access to the system. This PDF file can be offered to the user as an attachment to an e-mail or via a website.
Adobe has not provided any timetable for when the security fixes will be released, but it will probably take place earlier than the publication of the routine update that can be expected in October.
Until a security update is available, users are recommended to be careful not to open PDF documents from unknown sources, possibly also to install an alternative PDF reader instead of Abobes. An overview of a variety of options available on this page.
It is however under a month since the last time Adobe had to come up with an extraordinary security to your PDF products.
More details about the security hole and an attempt to exploit this is on this page.