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.
Advisories

No advisories yet.

Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

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'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: OX

Published:

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

cve-icon OpenCVE Enrichment

Updated: 2026-09-01T15:00:11Z

Weaknesses