An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command before authenticating. If running in high-security mode (default for community releases), only the attacker's own connection is terminated. If running in high-performance mode (default for Pro releases), all connections handled by the same managesieve-login process are terminated. Repeating the attack can cause denial of service for Sieve script management. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.
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 ManageSieve Service Denial of Service via Malformed Command dovecot: Dovecot: Denial of Service in ManageSieve login process
Weaknesses CWE-1286
References
Metrics threat_severity

None

threat_severity

Important


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

Type Values Removed Values Added
Metrics ssvc

{'options': {'Automatable': 'yes', 'Exploitation': 'none', 'Technical Impact': 'partial'}, 'version': '2.0.3'}


Fri, 28 Aug 2026 14:00:00 +0000

Type Values Removed Values Added
Title ManageSieve Service Denial of Service via Malformed Command

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

Type Values Removed Values Added
Description An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command before authenticating. If running in high-security mode (default for community releases), only the attacker's own connection is terminated. If running in high-performance mode (default for Pro releases), all connections handled by the same managesieve-login process are terminated. Repeating the attack can cause denial of service for Sieve script management. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.
Weaknesses CWE-400
References
Metrics cvssV3_1

{'score': 7.5, 'vector': 'CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H'}


cve-icon MITRE

Status: PUBLISHED

Assigner: OX

Published: 2026-08-28T10:12:13.963Z

Updated: 2026-08-28T15:55:19.368Z

Reserved: 2026-03-23T12:58:38.267Z

Link: CVE-2026-33605

cve-icon Vulnrichment

Updated: 2026-08-28T14:42:11.902Z

cve-icon NVD

Status : Received

Published: 2026-08-28T12:16:27.740

Modified: 2026-08-28T20:17:25.630

Link: CVE-2026-33605

cve-icon Redhat

Severity : Important

Publid Date: 2026-08-28T10:12:13Z

Links: CVE-2026-33605 - Bugzilla