Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. No publicly available exploits are known.

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Advisories

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Fixes

Solution

No solution given by the vendor.


Workaround

No workaround given by the vendor.

History

Mon, 18 May 2026 17:45:00 +0000

Type Values Removed Values Added
First Time appeared Dovecot
Dovecot dovecot
Open-xchange dovecot
CPEs cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*
cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*
Vendors & Products Dovecot
Dovecot dovecot
Open-xchange dovecot

Tue, 12 May 2026 16:15:00 +0000

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

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


Tue, 12 May 2026 15:45:00 +0000

Type Values Removed Values Added
Title CPU Time Limit Bypass for Sieve Scripts in Open‑Xchange OX Dovecot Pro

Tue, 12 May 2026 14:00:00 +0000

Type Values Removed Values Added
Description Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. No publicly available exploits are known.
Weaknesses CWE-400
References
Metrics cvssV3_1

{'score': 5.3, 'vector': 'CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:N/I:N/A:H'}


Projects

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cve-icon MITRE

Status: PUBLISHED

Assigner: OX

Published:

Updated: 2026-05-12T15:38:42.912Z

Reserved: 2026-04-08T09:59:59.342Z

Link: CVE-2026-40016

cve-icon Vulnrichment

Updated: 2026-05-12T15:38:39.723Z

cve-icon NVD

Status : Analyzed

Published: 2026-05-12T14:17:03.570

Modified: 2026-05-18T17:34:37.057

Link: CVE-2026-40016

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-05-12T16:00:12Z

Weaknesses