dovecot: When mail_max_userip_connections is set (default 10) and reached, submission-login can crash with epoll() panic cause...
CVE-2026-33263 is fixed in 12 products on 1 platform, first by RHSA-2026:79371, released August 28, 2026. It is not reported as exploited. Patch Radar priority: High.
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.
Where it's fixed
| Product | Fixed in | Fix | Released |
|---|---|---|---|
| Linux | |||
| dovecot · Debian 12.15 (bookworm) | 1:2.3.19.1+dfsg1-2.1+deb12u7 | DEBIAN-CVE-2026-33263 | Sep 10, 2026 |
| dovecot · Debian 13.5 (trixie) | 1:2.4.1+dfsg1-6+deb13u7 | DEBIAN-CVE-2026-33263 | Sep 10, 2026 |
| dovecot · Debian 14 | 1:2.4.5+dfsg1-1 | DEBIAN-CVE-2026-33263 | Sep 10, 2026 |
| dovecot · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot · RHEL 10 | 2.3.21-19.el10_2.8 | RHSA-2026:79371 | Aug 28, 2026 |
| dovecot · RHEL 8 | 1:2.3.16-16.el8_10 | RHSA-2026:76763 | Oct 6, 2026 |
| dovecot · RHEL 9 | 1:2.3.16-18.el9_8.8 | RHSA-2026:80825 | Oct 13, 2026 |
| dovecot · almalinux 10 | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 | Oct 8, 2026 |
| dovecot · almalinux 8 | 1:2.3.16-16.el8_10 | ALSA-2026:76763 | Oct 6, 2026 |
| dovecot · almalinux 9 | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 | Nov 7, 2026 |
| dovecot · ol 10 | 1:2.3.21-19.el10_2.8 | ELSA-2026-79371 | Oct 8, 2026 |
| dovecot · ol 8 | 1:2.3.16-16.el8_10 | ELSA-2026-76763 | Oct 6, 2026 |
| dovecot · ol 9 | 1:2.3.16-18.el9_8.8 | ELSA-2026-80825 | Nov 7, 2026 |
| dovecot · rocky 10 | 1:2.3.21-19.el10_2.8 | RLSA-2026:79371 | Nov 7, 2026 |
| dovecot · rocky 8 | 1:2.3.16-16.el8_10 | RLSA-2026:76763 | Oct 7, 2026 |
| dovecot · rocky 9 | 1:2.3.16-18.el9_8.8 | RLSA-2026:80825 | Nov 7, 2026 |
| dovecot-debuginfo · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-debugsource · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-devel · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-devel · RHEL 8 | 1:2.3.16-16.el8_10 | RHSA-2026:76763 | Oct 6, 2026 |
| dovecot-devel · RHEL 9 | 1:2.3.16-18.el9_8.8 | RHSA-2026:80825 | Oct 13, 2026 |
| dovecot-devel · almalinux 10 | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 | Oct 8, 2026 |
| dovecot-devel · almalinux 8 | 1:2.3.16-16.el8_10 | ALSA-2026:76763 | Oct 6, 2026 |
| dovecot-devel · almalinux 9 | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 | Nov 7, 2026 |
| dovecot-devel · ol 10 | 1:2.3.21-19.el10_2.8 | ELSA-2026-79371 | Oct 8, 2026 |
| dovecot-devel · ol 8 | 1:2.3.16-16.el8_10 | ELSA-2026-76763 | Oct 6, 2026 |
| dovecot-devel · ol 9 | 1:2.3.16-18.el9_8.8 | ELSA-2026-80825 | Nov 7, 2026 |
| dovecot-mysql · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-mysql · RHEL 8 | 1:2.3.16-16.el8_10 | RHSA-2026:76763 | Oct 6, 2026 |
| dovecot-mysql · RHEL 9 | 1:2.3.16-18.el9_8.8 | RHSA-2026:80825 | Oct 13, 2026 |
| dovecot-mysql · almalinux 10 | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 | Oct 8, 2026 |
| dovecot-mysql · almalinux 8 | 1:2.3.16-16.el8_10 | ALSA-2026:76763 | Oct 6, 2026 |
| dovecot-mysql · almalinux 9 | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 | Nov 7, 2026 |
| dovecot-mysql · ol 10 | 1:2.3.21-19.el10_2.8 | ELSA-2026-79371 | Oct 8, 2026 |
| dovecot-mysql · ol 8 | 1:2.3.16-16.el8_10 | ELSA-2026-76763 | Oct 6, 2026 |
| dovecot-mysql · ol 9 | 1:2.3.16-18.el9_8.8 | ELSA-2026-80825 | Nov 7, 2026 |
| dovecot-mysql-debuginfo · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-pgsql · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-pgsql · RHEL 8 | 1:2.3.16-16.el8_10 | RHSA-2026:76763 | Oct 6, 2026 |
| dovecot-pgsql · RHEL 9 | 1:2.3.16-18.el9_8.8 | RHSA-2026:80825 | Oct 13, 2026 |
| dovecot-pgsql · almalinux 10 | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 | Oct 8, 2026 |
| dovecot-pgsql · almalinux 8 | 1:2.3.16-16.el8_10 | ALSA-2026:76763 | Oct 6, 2026 |
| dovecot-pgsql · almalinux 9 | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 | Nov 7, 2026 |
| dovecot-pgsql · ol 10 | 1:2.3.21-19.el10_2.8 | ELSA-2026-79371 | Oct 8, 2026 |
| dovecot-pgsql · ol 8 | 1:2.3.16-16.el8_10 | ELSA-2026-76763 | Oct 6, 2026 |
| dovecot-pgsql · ol 9 | 1:2.3.16-18.el9_8.8 | ELSA-2026-80825 | Nov 7, 2026 |
| dovecot-pgsql-debuginfo · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-pigeonhole · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot-pigeonhole · RHEL 8 | 1:2.3.16-16.el8_10 | RHSA-2026:76763 | Oct 6, 2026 |
| dovecot-pigeonhole · RHEL 9 | 1:2.3.16-18.el9_8.8 | RHSA-2026:80825 | Oct 13, 2026 |
| dovecot-pigeonhole · almalinux 10 | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 | Oct 8, 2026 |
| dovecot-pigeonhole · almalinux 8 | 1:2.3.16-16.el8_10 | ALSA-2026:76763 | Oct 6, 2026 |
| dovecot-pigeonhole · almalinux 9 | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 | Nov 7, 2026 |
| dovecot-pigeonhole · ol 10 | 1:2.3.21-19.el10_2.8 | ELSA-2026-79371 | Oct 8, 2026 |
| dovecot-pigeonhole · ol 8 | 1:2.3.16-16.el8_10 | ELSA-2026-76763 | Oct 6, 2026 |
| dovecot-pigeonhole · ol 9 | 1:2.3.16-18.el9_8.8 | ELSA-2026-80825 | Nov 7, 2026 |
| dovecot-pigeonhole-debuginfo · Fedora 43 | 1:2.4.5-1.fc43 | FEDORA-2026-E8A6485109 | Sep 10, 2026 |
| dovecot23 · sles 15.6 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 | Sep 14, 2026 |
| dovecot23 · sles 15.7 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 | Sep 14, 2026 |
| dovecot24 · opensuse-leap 16.0 | 2.4.4-160000.2.1 | OPENSUSE-SU-2026:21720-1 | Sep 1, 2026 |
| dovecot24 · sles 16.0 | 2.4.4-160000.2.1 | SUSE-SU-2026:23595-1 | Sep 1, 2026 |
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