Quick answers
- Is CVE-2026-40015 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-40015 being exploited in the wild.
- How severe is CVE-2026-40015?
- 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 through 2.3.22.1, 3.0.0 through 3.0.6, 3.1.0 through 3.1.5.
- Is there a fix for CVE-2026-40015?
- 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-2026-40015 attacked?
- It is attacked over the network, in a hosted service.
- Am I affected by CVE-2026-40015?
- 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 flaw in the IMAP hibernation service component. An attacker with valid IMAP credentials can establish multiple connections and transmit invalid commands, triggering an out-of-bounds memory read that crashes the imap-hibernate process. The attack requires authentication and network access to the IMAP service. Successful exploitation causes service interruption for hibernated IMAP sessions. Patches are available in OX Dovecot Pro versions 2.3.22.2, 3.0.7, and 3.1.6 or later.
Affected products
- Open-Xchange Dovecot Pro 2.3.0 through 2.3.22.1, 3.0.0 through 3.0.6, 3.1.0 through 3.1.5
Timeline
- 2026-08-28: disclosed
- 2026-08-26: advisory: Initial advisory release