CVE-2026-42395: Open-Xchange GmbH Ox Dovecot CE

Medium severity, CVSS 4.3. EPSS: 0.4% chance of exploitation in the next 30 days.

A host listed as a trusted proxy can send forwarding information containing a NUL byte, which crashes the login process on the following login attempt. The login process is terminated, which can cause degradation or denial of service for logins. 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 2.3.0, before 2.4.5 (fixed in 2.4.5)
• Open-Xchange GmbH Ox Dovecot Pro: from 2.3.0, 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.