Adobe has published a security bulletin APSB09-15 for security issues 
leading to denial of service, addressed in Adobe Reader and Acrobat products:

  http://www.adobe.com/support/security/bulletins/apsb09-15.html

Quoting Adobe bulletin APSB09-15 for issues descriptions:

  This update resolves a XMP-XML entity expansion issue that could lead to
  a Denial of Service (DoS) attack (CVE-2009-2979).
  
  This update resolves an input validation issue that could lead to a Denial
  of Service (DoS) issue (CVE-2009-2988).

  This update resolves an integer overflow in Acrobat that leads to a Denial
  of Service (DoS) (CVE-2009-2995).

  This update resolves a stack overflow issue that could potentially lead
  to a Denial of Service (DoS) attack (CVE-2009-3431).