CVE-2026-32661Known exploitationNetwork attack vector

Unauthenticated code execution via pop3wallpasswd stack overflow

Published May 13, 2026 · Updated May 13, 2026

Stack overflow in Canon Marketing Japan GUARDIANWALL products allows remote attackers to execute code through the management web service. The pop3wallpasswd command overflows a stack buffer while handling a crafted web request; the vendor has not disclosed the exact unsafe operation. The flaw affects MailSuite 1.4.00 through 2.4.26 and Mail Security Cloud versions before the April 30, 2026 maintenance only when pop3wallpasswd runs with grdnwww user privilege; attacks against on-premises deployments have been observed.

CVSS severity9.3
Critical
EPSS probability0.47%
Next 30 days · Sep 16, 2026
Known exploitationReported
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Stack overflow in Canon Marketing Japan GUARDIANWALL products allows remote attackers to execute code through the management web service. The pop3wallpasswd command overflows a stack buffer while handling a crafted web request; the vendor has not disclosed the exact unsafe operation. The flaw affects MailSuite 1.4.00 through 2.4.26 and Mail Security Cloud versions before the April 30, 2026 maintenance only when pop3wallpasswd runs with grdnwww user privilege; attacks against on-premises deployments have been observed.

The record

CVE
CVE-2026-32661
Published
May 13, 2026
Updated
May 13, 2026
Vendor
Canon Marketing Japan Inc.
Product
GUARDIANWALL Mail Security Cloud
Classifications
CWE-121, T1190
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. May 13, 2026CVE publishedPublication date reported by the CVE source.
  2. May 13, 2026Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=2026
  2. Affected versionversion=versions before the maintenance on April 30

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

Canon Marketing Japan Inc. · GUARDIANWALL Mail Security Cloudversion=2026; version=versions before the maintenance on April 30
Canon Marketing Japan Inc. · GUARDIANWALL MailSuiteversion=Ver 1.4.00 to Ver 2.4.26

Published CVSS scores

9.8JPCERT/CCCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
9.3JPCERT/CCCVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:N/VC:H/VI:H/VA:H/SC:N/SI:N/SA:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

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No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationReported
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-121Stack-based Buffer Overflow
T1190Exploit Public-Facing Application

Public exploit references

No public exploit references are available in this record.

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Reported exploitation

Technologies

Your stack

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Your stack

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