JVN#35567473    
Critical GUARDIANWALL MailSuite vulnerable to stack-based buffer overflow

GUARDIANWALL MailSuite provided by Canon Marketing Japan Inc. contains a stack-based buffer overflow vulnerability.

• GUARDIANWALL MailSuite (On-premises version) Ver 1.4.00 to Ver 2.4.26
• GUARDIANWALL Mail Security Cloud (SaaS version) versions before the maintenance on April 30, 2026

GUARDIANWALL MailSuite provided by Canon Marketing Japan Inc. contains the following vulnerability.

• Stack-based buffer overflow in pop3wallpasswd command (CWE-121)
  • CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N Base Score 9.3
  • CVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H Base Score 9.8
  • CVE-2026-32661
  • This can be exploited only when the product is configured to run pop3wallpasswd with grdnwww user privilege

The developer states that attacks exploiting the vulnerability has been observed in GUARDIANWALL MailSuite (On-premises version).

If a remote attacker sends a specially crafted request to the product's web service, arbitrary code may be executed.

Apply the patch
Apply all the patches provided by the developer.

Note that, GUARDIANWALL Mail Security Cloud (SaaS version) has already been fixed with April 30, 2026 updates.

Apply the Workaround
The developer recommends the users to follow the workaround until applying the patch.

For more details, refer to the information provided by the developer.

Vendor	Status	Last Update	Vendor Notes
Canon Marketing Japan Inc.	Vulnerable	2026/05/13	Canon Marketing Japan Inc. website

Canon Marketing Japan Inc. reported this vulnerability to JPCERT/CC to notify users of its solution through JVN. JPCERT/CC and Canon Marketing Japan Inc. coordinated under the Information Security Early Warning Partnership.