CVE-2026-27859

Medium

Description

A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. No publicly available exploits are known.

SeverityMedium

CVSS5.3

Exploit probability—

ProductDovecot

PublishedMar 27, 2026

First seenMar 27, 2026

Weakness typeCWE-400Uncontrolled resource consumption

How to fix

Update

dovecot dovecot2.4.3 or later
open-xchange dovecot3.0.5, 3.1.4 or later

Vendor advisories

documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.json

Affected products

Product	Affected versions	Fixed in
dovecot dovecot	v < 2.4.3	2.4.3
open-xchange dovecot	v < 3.0.5, 3.1.0 ≤ v < 3.1.4	3.0.5, 3.1.4

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