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
Published · last modified .
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.
EPSS exploit prediction
EPSS: 0.002 (13.4th percentile), scored .
Very low probability of exploitation in the next 30 days; routine patching cadence is appropriate. 13th percentile — 13.4% of CVEs in the catalogue have a lower EPSS than this one. How to read EPSS.
EPSS over last 30 days · oldest: 0.002 · newest: 0.002 · change: +0.000
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.