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CVE-2026-33263

Опубликовано: 28 авг. 2026
Источник: redhat
CVSS3: 7.1
EPSS Низкий

Описание

When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.

A flaw was found in the Dovecot mail server's submission-login component. This vulnerability occurs when the server reaches its maximum allowed user IP connections, leading to a crash due to file descriptor handling issues. This can result in a denial of service, preventing users from sending emails, and potentially causing duplicate message delivery under certain conditions.

Меры по смягчению последствий

To mitigate this issue, limit the number of connections handled by a single submission-login process. This can be achieved by adjusting the process_limit setting for the submission-login service in the Dovecot configuration. For example, add or modify the following in a Dovecot configuration file (e.g., /etc/dovecot/conf.d/10-master.conf):

service submission-login { process_limit = <lower_value> }

Reducing this limit may impact performance. After modifying the configuration, restart the Dovecot service for the changes to take effect.

Затронутые пакеты

ПлатформаПакетСостояниеРекомендацияРелиз
Red Hat Enterprise Linux 10dovecotAffected
Red Hat Enterprise Linux 6dovecotOut of support scope
Red Hat Enterprise Linux 7dovecotAffected
Red Hat Enterprise Linux 8dovecotAffected
Red Hat Enterprise Linux 9dovecotAffected

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Дополнительная информация

Статус:

Important
Дефект:
CWE-910
https://bugzilla.redhat.com/show_bug.cgi?id=2525567dovecot: Dovecot: Denial of Service and potential message duplication via connection limit exhaustion

EPSS

Процентиль: 21%
0.0029
Низкий

7.1 High

CVSS3

Связанные уязвимости

CVSS3: 4.3
ubuntu
17 дней назад

When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.

CVSS3: 4.3
nvd
17 дней назад

When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.

CVSS3: 4.3
debian
17 дней назад

When mail_max_userip_connections is set (default 10) and reached, subm ...

CVSS3: 4.3
github
17 дней назад

When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic caused by file descriptor handling issues. If running in high-security mode (default for community releases), only the new submission connection gets terminated. If running in high-performance mode (default for Pro releases), all connections handled by the submission-login process will be terminated. The crashes can cause failure for user to send a message, or it can cause duplicate messages to be sent. If TLS is not used (in the backend server processing the submission), duplicate deliveries cannot happen, because the crash can only happen at AUTH stage. Limit the number of connections handled by single submission-login process. This has a performance impact though. Update to non-vulnerable version. No publicly available exploits are known.

suse-cvrf
13 дней назад

Security update for dovecot24

EPSS

Процентиль: 21%
0.0029
Низкий

7.1 High

CVSS3