CVE-2026-42391
Description
An unauthenticated attacker can send an IMAP ID command with a very large number of parameters before logging in, which causes memory and CPU usage to grow disproportionately. The login process can be terminated by the out-of-memory handling, which also terminates all other connections handled by the same process. This can cause degradation or denial of service for IMAP logins. Limit the number of connections handled by a single imap-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.
How to fix
- Open-Xchange GmbH OX Dovecot Pro2.3.22.2, 3.0.7, 3.1.6 or later
- Open-Xchange GmbH OX Dovecot CE2.4.5 or later
Affected products
| Product | Affected versions | Fixed in |
|---|---|---|
| Open-Xchange GmbH OX Dovecot Pro | 2.3.0 ≤ v < 2.3.22.2, 3.0.0 ≤ v < 3.0.7, 3.1.0 ≤ v < 3.1.6 | 2.3.22.2, 3.0.7, 3.1.6 |
| Open-Xchange GmbH OX Dovecot CE | 2.3.0 ≤ v < 2.4.5 | 2.4.5 |
Check your version
Choose the product and enter the version you run to see whether it falls in the affected range.
Attack Surface Management
See the assets tied to your domains, the technologies they run and known vulnerabilities in one list.