Integer signedness error in the authentication functionality in librpc.dll in the Informix Storage Manager (ISM) Portmapper service (aka portmap.exe), as used in IBM Informix Dynamic Server (IDS) 10.x before 10.00.TC9 and 11.x before 11.10.TC3 and EMC Legato NetWorker, allows remote attackers to execute arbitrary code via a crafted parameter size that triggers a stack-based buffer overflow.