Quick answers
- Is CVE-2026-42395 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-42395 being exploited in the wild.
- How severe is CVE-2026-42395?
- Medium severity, with a CVSS score of 4.3, published 28 August 2026.
- Which products and versions are affected?
- Open-Xchange Dovecot Pro 2.3.0 to 2.3.22.1, 3.0.0 to 3.0.6, 3.1.0 to 3.1.5.
- Is there a fix for CVE-2026-42395?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-42395 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-42395?
- Check whether you run Open-Xchange Dovecot Pro at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
The vulnerability is a denial-of-service condition in OX Dovecot Pro's login process triggered by malformed forwarding headers from a host configured as a trusted proxy. When a trusted proxy sends forwarding information containing a NUL byte, the login process crashes on the next authentication attempt, terminating the session. The attack vector is network-based and requires the attacker to control or compromise a host listed in the trusted proxy configuration. No publicly available exploits are known. Affected versions: 2.3.0–2.3.22.1, 3.0.0–3.0.6, and 3.1.0–3.1.5; patched versions are 2.3.22.2, 3.0.7, and 3.1.6.
Affected products
- Open-Xchange Dovecot Pro 2.3.0 to 2.3.22.1, 3.0.0 to 3.0.6, 3.1.0 to 3.1.5
Timeline
- 2026-08-28: disclosed: CVE-2026-42395 publicly disclosed