NASM is an 80x86 assembler.
Two stack based buffer overflow bugs have been found in nasm. An attacker could create an ASM file in such a way that when compiled by a victim, could execute arbitrary code on their machine. The Common Vulnerabilities and Exposures project (cve.mitre.org) has assigned the names CAN-2004-1287 and CAN-2005-1194 to these issues.
All users of nasm are advised to upgrade to this updated package, which contains backported fixes for these issues.