CVE-2006-5551

CVE-2006-5551 describes a stack-based buffer overflow vulnerability in QK SMTP version 3.01 and earlier. This flaw allows remote attackers to execute arbitrary code by sending an excessively long argument to the RCPT TO command. With a CVSS score of 7.5, this vulnerability is considered highly severe due to its network-based attack vector, low attack complexity, and potential for complete compromise of confidentiality, integrity, and availability. While not listed in CISA's KEV catalog, multiple public exploits exist on ExploitDB demonstrating both denial-of-service and remote code execution, though there is no evidence of widespread active exploitation or significant community discussion.