PDF files are often used for exchanging documents between corporations and individuals, and are considered quite secure regarding the potential to contain malicious program code.

However, critical vulnerabilities have now been identified in Adobe Reader and Adobe Acrobat. These vulernabilities could allow an attacker to take control of the affected system. Exploit code that utilizes these vulnerabilities has been seen in the wild.

Adobe has published an update that resolves these vulnerabilities. More information in Abobe's Security bulletin where there are also links to downloading the latest version

Norman advices all affected users to update to  Adobe Reader 8.1.1 or Acrobat 8.1.1.