Auth bypass in Open-Xchange Gmbh Ox Dovecot Ce

CVE-2026-42008

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.

Vulnerability class: Broken Authentication

CVSS v3 metric

CVSS v3 base score 4.3 (Medium). Vector: CVSS:3.1/AV:A/AC:L/PR:N/UI:N/S:U/C:N/I:L/A:N.

Affected products

Weakness classification (CWE)

References

Frequently asked questions

What is CVE-2026-42008?
CVE-2026-42008 is a medium-severity vulnerability in Open-Xchange Gmbh Ox Dovecot Ce, classified under Improper Authentication. CVSS score: 4.3/10. Published 2026-08-28.
How severe is CVE-2026-42008?
Medium severity. CVSS v3 base score is 4.3 out of 10.