CVE-2026-40019

Medium

Description

An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spin in an infinite loop consuming CPU. This can cause degradation or denial of service for Sieve script management, and repeated connections can consume all available CPU on the server. Monitor system for abnormal CPU usage and kill the offending process. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.

SeverityMedium

CVSS5.9

Exploit probability—

ProductOX Dovecot CE

PublishedAug 28, 2026

First seenAug 28, 2026

Weakness typeCWE-400Uncontrolled resource consumption

How to fix

Update

Open-Xchange GmbH OX Dovecot CE2.4.5 or later

Vendor advisories

documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0003.json

Affected products

Product	Affected versions	Fixed in
Open-Xchange GmbH OX Dovecot CE	2.4.3 ≤ v < 2.4.5	2.4.5

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