When the mail_max_userip_connections limit of 10 is reached, the submission‑login process may crash with an epoll() panic due to improper file‑descriptor handling. The crash terminates either only the new connection (in high‑security mode) or all connections managed by the submission‑login process (in high‑performance mode). This disrupts the user’s ability to send mail and can cause duplicate messages when TLS is not used, since the crash can only occur at the AUTH stage. The flaw does not compromise confidentiality or allow unauthorized access, but it does interrupt service availability. This weakness is consistent with CWE-403 and CWE-910.

The vulnerability affects Open‑Xchange GmbH’s OX Dovecot CE and OX Dovecot Pro products. No specific firmware or software version numbers are listed in the advisory; however, any version running the affected configuration is potentially impacted.

The CVSS base score of 4.3 places this issue in the low‑to‑moderate severity range. The EPSS score of 0.0029 (less than 1%) indicates a very low but non‑zero exploitation probability, and the vulnerability is not listed in the CISA KEV catalog. Because the crash can be triggered by sending many connections to the mail submission service, remote attackers who can reach the Dovecot server can potentially execute a denial‑of‑service attack by exhausting the allowed connections per IP. No publicly known exploits are available, but the attack requires only normal mail‑submission traffic and can be automated. Mitigation is best achieved by applying the vendor’s fixed version.