The digital signature mechanism for the Adobe Acrobat PDF viewer only verifies the PE header of executable code for a plug-in, which can allow attackers to execute arbitrary code in certified mode by making the plug-in appear to be signed by Adobe.
libCoolType library as used in Adobe Acrobat (acroread) on Linux creates the AdobeFnt.lst file with world-writable permissions, which allows local users to modify the file and possibly modify acroread's behavior.
Buffer overflow in Adobe Acrobat 4.05, Reader, Business Tools, and Fill In products that handle PDF files allows attackers to execute arbitrary commands via a long /Registry or /Ordering specifier.