CVE-2026-42008: Open-Xchange GmbH Ox Dovecot CE

Medium severity, CVSS 4.3. EPSS: 0.2% chance of exploitation in the next 30 days.

Forwarding information received from a host listed as a trusted proxy is not kept separate from Dovecot's own authentication fields, so a value sent by that host can be injected as an internal authentication field. Any host permitted to act as a trusted proxy can authenticate as any user without knowing that user's password. This affects deployments whose password database honours a field that permits authentication without a password. Deployments that do not configure trusted proxies are not affected. Restrict the list of trusted proxy networks to hosts that are fully under your control. Update to non-vulnerable version. No publicly available exploits are known.

Affected products

• Open-Xchange GmbH Ox Dovecot CE: from 2.3.4, before 2.4.5 (fixed in 2.4.5)
• Open-Xchange GmbH Ox Dovecot Pro: from 2.3.4, before 2.3.22.2 (fixed in 2.3.22.2); from 3.0.0, before 3.0.7 (fixed in 3.0.7); from 3.1.0, before 3.1.6 (fixed in 3.1.6)

Published 2026-08-28. Last modified 2026-09-03.