CVE-2026-42008 Auth bypass in OX Dovecot CE
A trusted proxy can inject authentication fields to bypass password checks and log in as any user in Dovecot deployments with specific password database configurations.
- Exploited in the wild
- Not known
- Login needed
- Not needed
- Attackable
- Local or same network only
- Victim action needed
- Not needed
- Fix
- Available
What is CVE-2026-42008?
CVE-2026-42008 is a medium-severity authentication bypass vulnerability in Open-Xchange GmbH OX Dovecot CE, published on 28 Aug 2026. It can only be exploited from the same machine or local network, with no action from the victim.
Official description
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.
Weakness: CWE-287
Which versions are affected by CVE-2026-42008?
How do I fix CVE-2026-42008?
Upgrade to a fixed version.
Upgrade, and rotate credentials and sessions that may have been exposed. More about Authentication bypass.
Is CVE-2026-42008 being exploited?
There is no known exploitation of CVE-2026-42008 in the wild and no public exploit code.
Sources
Also known as AZL-98325, DEBIAN-CVE-2026-42008, GHSA-hwmp-h522-jmhg, UBUNTU-CVE-2026-42008.