CVE-2026-33607

Severity: medium (CVSS 4.3 v3.1)
Exploited in the wild: not listed in CISA KEV
EPSS: 0.6% probability of exploitation in the next 30 days
Public exploit or detection template: none known
Published: 2026-08-28 · updated 2026-09-03
Weakness: CWE-400

Description

An attacker that has valid credentials can use IMAP LIST command to consume CPU. This can cause degradation or denial of service for IMAP. Monitor system for abnormal CPU usage and kill the offending process and lock account. Alternatively install fixed version. No publicly available exploits are known.

Affected products

Open-Xchange GmbH OX Dovecot CE: from 2.3.0 before 2.4.5 — fixed in 2.4.5
Open-Xchange GmbH OX Dovecot Pro: from 2.3.0 before 3.0.7; from 3.1.0 before 3.1.6 — fixed in 3.0.7, 3.1.6

How to fix

Upgrade to a fixed version: Open-Xchange GmbH OX Dovecot CE 2.4.5; Open-Xchange GmbH OX Dovecot Pro 3.0.7, 3.1.6. Check the vendor advisory for mitigations.

References

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

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