Canon Marketing Japan Inc. - Guardianwall Mailsuite (on-premises Version) - CRITICAL - CVE-2026-32661. A stack-based buffer overflow vulnerability exists in GUARDIANWALL MailSuite and GUARDIANWALL Mail Security Cloud. An attacker can exploit this vulnerability by sending a specially crafted request to the web service of the affected product. If the application is configured to run pop3wallpasswd with grdnwww user privileges, it may lead to the execution of arbitrary code, posing a significant risk to the integrity and security of the system.