Description
An attacker that can get Dovecot to relay a message, for example through Sieve redirect or submission relay, can use a crafted line ending in the message body to bypass the outbound protection that prevents message content from being interpreted as SMTP commands. A downstream mail server that hasn't yet fixed the SMTP smuggling vulnerability can be tricked into treating part of the message body as new SMTP commands, allowing injection of spoofed email. This is the same vulnerability class as CVE-2023-51764 and CVE-2023-51766. Where you control the receiving mail servers, ensure they reject bare carriage returns in message data. Update to non-vulnerable version. No publicly available exploits are known.
Published: 2026-08-28
Score: 5.9 Medium
EPSS: < 1% Very Low
KEV: No
Impact: n/a
Action: n/a
AI Analysis

Analysis and contextual insights are available on OpenCVE Cloud.

Remediation

No vendor fix or workaround currently provided.

Additional remediation guidance may be available on OpenCVE Cloud.

Tracking

Sign in to view the affected projects.

Advisories

No advisories yet.

History

Tue, 01 Sep 2026 14:45:00 +0000

Type Values Removed Values Added
First Time appeared Open-xchange
Open-xchange ox Dovecot Ce
Open-xchange ox Dovecot Pro
Vendors & Products Open-xchange
Open-xchange ox Dovecot Ce
Open-xchange ox Dovecot Pro

Tue, 01 Sep 2026 12:15:00 +0000

Type Values Removed Values Added
Title SMTP Smuggling via Dovecot Message Body Manipulation dovecot: Dovecot: SMTP smuggling vulnerability allows spoofed email injection
Weaknesses CWE-93
References
Metrics threat_severity

None

threat_severity

Moderate


Fri, 28 Aug 2026 21:30:00 +0000

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'no', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 28 Aug 2026 13:00:00 +0000

Type Values Removed Values Added
Title SMTP Smuggling via Dovecot Message Body Manipulation

Fri, 28 Aug 2026 11:30:00 +0000

Type Values Removed Values Added
Description An attacker that can get Dovecot to relay a message, for example through Sieve redirect or submission relay, can use a crafted line ending in the message body to bypass the outbound protection that prevents message content from being interpreted as SMTP commands. A downstream mail server that hasn't yet fixed the SMTP smuggling vulnerability can be tricked into treating part of the message body as new SMTP commands, allowing injection of spoofed email. This is the same vulnerability class as CVE-2023-51764 and CVE-2023-51766. Where you control the receiving mail servers, ensure they reject bare carriage returns in message data. Update to non-vulnerable version. No publicly available exploits are known.
Weaknesses CWE-655
References
Metrics cvssV3_1

{'score': 5.9, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:H/A:N'}


Subscriptions

Open-xchange Ox Dovecot Ce Ox Dovecot Pro
cve-icon MITRE

Status: PUBLISHED

Assigner: OX

Published:

Updated: 2026-08-28T15:55:26.026Z

Reserved: 2026-03-23T12:58:38.266Z

Link: CVE-2026-33604

cve-icon Vulnrichment

Updated: 2026-08-28T14:32:49.669Z

cve-icon NVD

Status : Received

Published: 2026-08-28T12:16:27.613

Modified: 2026-08-28T20:17:25.510

Link: CVE-2026-33604

cve-icon Redhat

Severity : Moderate

Publid Date: 2026-08-28T10:12:12Z

Links: CVE-2026-33604 - Bugzilla

cve-icon OpenCVE Enrichment

Updated: 2026-09-01T15:15:12Z

Weaknesses