CVE-2026-33263
Fixed in a distro release EPSS <1%CVSS 4.3
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.
Products: Open-Xchange GmbH OX Dovecot Pro, Open-Xchange GmbH OX Dovecot CE
Distro releases
| Release | Package | Fixed in |
|---|---|---|
| AlmaLinux 10 | dovecot | 1:2.3.21-19.el10_2.8 |
| AlmaLinux 10 | dovecot-devel | 1:2.3.21-19.el10_2.8 |
| AlmaLinux 10 | dovecot-mysql | 1:2.3.21-19.el10_2.8 |
| AlmaLinux 10 | dovecot-pgsql | 1:2.3.21-19.el10_2.8 |
| AlmaLinux 10 | dovecot-pigeonhole | 1:2.3.21-19.el10_2.8 |
| AlmaLinux 8 | dovecot | 1:2.3.16-16.el8_10 |
| AlmaLinux 8 | dovecot-devel | 1:2.3.16-16.el8_10 |
| AlmaLinux 8 | dovecot-mysql | 1:2.3.16-16.el8_10 |
| AlmaLinux 8 | dovecot-pgsql | 1:2.3.16-16.el8_10 |
| AlmaLinux 8 | dovecot-pigeonhole | 1:2.3.16-16.el8_10 |
| AlmaLinux 9 | dovecot | 1:2.3.16-18.el9_8.8 |
| AlmaLinux 9 | dovecot-devel | 1:2.3.16-18.el9_8.8 |
| AlmaLinux 9 | dovecot-mysql | 1:2.3.16-18.el9_8.8 |
| AlmaLinux 9 | dovecot-pgsql | 1:2.3.16-18.el9_8.8 |
| AlmaLinux 9 | dovecot-pigeonhole | 1:2.3.16-18.el9_8.8 |
| Alpine 3.23 | dovecot | 2.4.5-r0 |
| Alpine 3.24 | dovecot | 2.4.5-r0 |
| Debian 12 | dovecot | no fix |
| Debian 13 | dovecot | 1:2.4.1+dfsg1-6+deb13u7 |
| Debian 14 | dovecot | 1:2.4.5+dfsg1-1 |
| Red Hat Enterprise Linux 10.2 | dovecot | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-debuginfo | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-debugsource | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-devel | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-mysql | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-mysql-debuginfo | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-pgsql | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-pgsql-debuginfo | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-pigeonhole | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 10.2 | dovecot-pigeonhole-debuginfo | 1:2.3.21-19.el10_2.8 |
| Red Hat Enterprise Linux 8 | dovecot | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-debuginfo | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-debugsource | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-devel | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-mysql | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-mysql-debuginfo | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-pgsql | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-pgsql-debuginfo | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-pigeonhole | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 8 | dovecot-pigeonhole-debuginfo | 1:2.3.16-16.el8_10 |
| Red Hat Enterprise Linux 9 | dovecot | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-debuginfo | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-debugsource | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-devel | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-mysql | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-mysql-debuginfo | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-pgsql | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-pgsql-debuginfo | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-pigeonhole | 1:2.3.16-18.el9_8.8 |
| Red Hat Enterprise Linux 9 | dovecot-pigeonhole-debuginfo | 1:2.3.16-18.el9_8.8 |
| Rocky Linux 10 | dovecot | 1:2.3.21-19.el10_2.8 |
| Rocky Linux 8 | dovecot | 1:2.3.16-16.el8_10 |
| Rocky Linux 9 | dovecot | 1:2.3.16-18.el9_8.8 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-ESPOS | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP4-LTSS | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP5-ESPOS | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise High Performance Computing 15 SP5-LTSS | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Module for Server Applications 15 SP7 | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Server 15 SP4-LTSS | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Server 15 SP5-LTSS | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Server 15 SP6-LTSS | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Server 16.0 | dovecot24 | 2.4.4-160000.2.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP4 | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP5 | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Server for SAP Applications 15 SP6 | dovecot23 | 2.3.21.1-150200.76.1 |
| SUSE Linux Enterprise Server for SAP applications 16.0 | dovecot24 | 2.4.4-160000.2.1 |
| Ubuntu 16.04 LTS | dovecot | no fix |
| Ubuntu 18.04 LTS | dovecot | no fix |
| Ubuntu 20.04 LTS | dovecot | no fix |
| Ubuntu 22.04 LTS | dovecot | no fix |
| Ubuntu 24.04 LTS | dovecot | no fix |
| Ubuntu 26.04 LTS | dovecot | no fix |
| Ubuntu Pro 14.04 LTS | dovecot | no fix |
| openSUSE Leap 16.0 | dovecot24 | 2.4.4-160000.2.1 |
| openSUSE Tumbleweed | dovecot24 | 2.4.5-1.1 |