# CVE-2026-33263: 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. - Web page: https://patchblox.com/security/cve/CVE-2026-33263 - Priority: High - CVSS: 9.1 (important) - EPSS: 0.0055 - CISA KEV: not listed - Exploited (vendor report): no - Publicly disclosed: no - Published: Aug 28, 2026 ## Description 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 | Platform | Product | Fixed in | Fix | Released | |---|---|---|---|---| | Linux | dovecot Debian 12.15 (bookworm) | 1:2.3.19.1+dfsg1-2.1+deb12u7 | [DEBIAN-CVE-2026-33263](https://patchblox.com/security/data/fix/linux/debian-cve-2026-33263.md) | Sep 10, 2026 | | Linux | dovecot Debian 13.5 (trixie) | 1:2.4.1+dfsg1-6+deb13u7 | [DEBIAN-CVE-2026-33263](https://patchblox.com/security/data/fix/linux/debian-cve-2026-33263.md) | Sep 10, 2026 | | Linux | dovecot Debian 14 | 1:2.4.5+dfsg1-1 | [DEBIAN-CVE-2026-33263](https://patchblox.com/security/data/fix/linux/debian-cve-2026-33263.md) | Sep 10, 2026 | | Linux | dovecot Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot RHEL 10 | 2.3.21-19.el10_2.8 | [RHSA-2026:79371](https://patchblox.com/security/data/fix/linux/rhsa-2026-79371.md) | Aug 28, 2026 | | Linux | dovecot RHEL 8 | 1:2.3.16-16.el8_10 | [RHSA-2026:76763](https://patchblox.com/security/data/fix/linux/rhsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot RHEL 9 | 1:2.3.16-18.el9_8.8 | [RHSA-2026:80825](https://patchblox.com/security/data/fix/linux/rhsa-2026-80825.md) | Oct 13, 2026 | | Linux | dovecot almalinux 10 | 1:2.3.21-19.el10_2.8 | [ALSA-2026:79371](https://patchblox.com/security/data/fix/linux/alsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot almalinux 8 | 1:2.3.16-16.el8_10 | [ALSA-2026:76763](https://patchblox.com/security/data/fix/linux/alsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot almalinux 9 | 1:2.3.16-18.el9_8.8 | [ALSA-2026:80825](https://patchblox.com/security/data/fix/linux/alsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot ol 10 | 1:2.3.21-19.el10_2.8 | [ELSA-2026-79371](https://patchblox.com/security/data/fix/linux/elsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot ol 8 | 1:2.3.16-16.el8_10 | [ELSA-2026-76763](https://patchblox.com/security/data/fix/linux/elsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot ol 9 | 1:2.3.16-18.el9_8.8 | [ELSA-2026-80825](https://patchblox.com/security/data/fix/linux/elsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot rocky 10 | 1:2.3.21-19.el10_2.8 | [RLSA-2026:79371](https://patchblox.com/security/data/fix/linux/rlsa-2026-79371.md) | Nov 7, 2026 | | Linux | dovecot rocky 8 | 1:2.3.16-16.el8_10 | [RLSA-2026:76763](https://patchblox.com/security/data/fix/linux/rlsa-2026-76763.md) | Oct 7, 2026 | | Linux | dovecot rocky 9 | 1:2.3.16-18.el9_8.8 | [RLSA-2026:80825](https://patchblox.com/security/data/fix/linux/rlsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-debuginfo Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-debugsource Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-devel Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-devel RHEL 8 | 1:2.3.16-16.el8_10 | [RHSA-2026:76763](https://patchblox.com/security/data/fix/linux/rhsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-devel RHEL 9 | 1:2.3.16-18.el9_8.8 | [RHSA-2026:80825](https://patchblox.com/security/data/fix/linux/rhsa-2026-80825.md) | Oct 13, 2026 | | Linux | dovecot-devel almalinux 10 | 1:2.3.21-19.el10_2.8 | [ALSA-2026:79371](https://patchblox.com/security/data/fix/linux/alsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-devel almalinux 8 | 1:2.3.16-16.el8_10 | [ALSA-2026:76763](https://patchblox.com/security/data/fix/linux/alsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-devel almalinux 9 | 1:2.3.16-18.el9_8.8 | [ALSA-2026:80825](https://patchblox.com/security/data/fix/linux/alsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-devel ol 10 | 1:2.3.21-19.el10_2.8 | [ELSA-2026-79371](https://patchblox.com/security/data/fix/linux/elsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-devel ol 8 | 1:2.3.16-16.el8_10 | [ELSA-2026-76763](https://patchblox.com/security/data/fix/linux/elsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-devel ol 9 | 1:2.3.16-18.el9_8.8 | [ELSA-2026-80825](https://patchblox.com/security/data/fix/linux/elsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-mysql Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-mysql RHEL 8 | 1:2.3.16-16.el8_10 | [RHSA-2026:76763](https://patchblox.com/security/data/fix/linux/rhsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-mysql RHEL 9 | 1:2.3.16-18.el9_8.8 | [RHSA-2026:80825](https://patchblox.com/security/data/fix/linux/rhsa-2026-80825.md) | Oct 13, 2026 | | Linux | dovecot-mysql almalinux 10 | 1:2.3.21-19.el10_2.8 | [ALSA-2026:79371](https://patchblox.com/security/data/fix/linux/alsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-mysql almalinux 8 | 1:2.3.16-16.el8_10 | [ALSA-2026:76763](https://patchblox.com/security/data/fix/linux/alsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-mysql almalinux 9 | 1:2.3.16-18.el9_8.8 | [ALSA-2026:80825](https://patchblox.com/security/data/fix/linux/alsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-mysql ol 10 | 1:2.3.21-19.el10_2.8 | [ELSA-2026-79371](https://patchblox.com/security/data/fix/linux/elsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-mysql ol 8 | 1:2.3.16-16.el8_10 | [ELSA-2026-76763](https://patchblox.com/security/data/fix/linux/elsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-mysql ol 9 | 1:2.3.16-18.el9_8.8 | [ELSA-2026-80825](https://patchblox.com/security/data/fix/linux/elsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-mysql-debuginfo Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-pgsql Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-pgsql RHEL 8 | 1:2.3.16-16.el8_10 | [RHSA-2026:76763](https://patchblox.com/security/data/fix/linux/rhsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-pgsql RHEL 9 | 1:2.3.16-18.el9_8.8 | [RHSA-2026:80825](https://patchblox.com/security/data/fix/linux/rhsa-2026-80825.md) | Oct 13, 2026 | | Linux | dovecot-pgsql almalinux 10 | 1:2.3.21-19.el10_2.8 | [ALSA-2026:79371](https://patchblox.com/security/data/fix/linux/alsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-pgsql almalinux 8 | 1:2.3.16-16.el8_10 | [ALSA-2026:76763](https://patchblox.com/security/data/fix/linux/alsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-pgsql almalinux 9 | 1:2.3.16-18.el9_8.8 | [ALSA-2026:80825](https://patchblox.com/security/data/fix/linux/alsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-pgsql ol 10 | 1:2.3.21-19.el10_2.8 | [ELSA-2026-79371](https://patchblox.com/security/data/fix/linux/elsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-pgsql ol 8 | 1:2.3.16-16.el8_10 | [ELSA-2026-76763](https://patchblox.com/security/data/fix/linux/elsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-pgsql ol 9 | 1:2.3.16-18.el9_8.8 | [ELSA-2026-80825](https://patchblox.com/security/data/fix/linux/elsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-pgsql-debuginfo Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-pigeonhole Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot-pigeonhole RHEL 8 | 1:2.3.16-16.el8_10 | [RHSA-2026:76763](https://patchblox.com/security/data/fix/linux/rhsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-pigeonhole RHEL 9 | 1:2.3.16-18.el9_8.8 | [RHSA-2026:80825](https://patchblox.com/security/data/fix/linux/rhsa-2026-80825.md) | Oct 13, 2026 | | Linux | dovecot-pigeonhole almalinux 10 | 1:2.3.21-19.el10_2.8 | [ALSA-2026:79371](https://patchblox.com/security/data/fix/linux/alsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-pigeonhole almalinux 8 | 1:2.3.16-16.el8_10 | [ALSA-2026:76763](https://patchblox.com/security/data/fix/linux/alsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-pigeonhole almalinux 9 | 1:2.3.16-18.el9_8.8 | [ALSA-2026:80825](https://patchblox.com/security/data/fix/linux/alsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-pigeonhole ol 10 | 1:2.3.21-19.el10_2.8 | [ELSA-2026-79371](https://patchblox.com/security/data/fix/linux/elsa-2026-79371.md) | Oct 8, 2026 | | Linux | dovecot-pigeonhole ol 8 | 1:2.3.16-16.el8_10 | [ELSA-2026-76763](https://patchblox.com/security/data/fix/linux/elsa-2026-76763.md) | Oct 6, 2026 | | Linux | dovecot-pigeonhole ol 9 | 1:2.3.16-18.el9_8.8 | [ELSA-2026-80825](https://patchblox.com/security/data/fix/linux/elsa-2026-80825.md) | Nov 7, 2026 | | Linux | dovecot-pigeonhole-debuginfo Fedora 43 | 1:2.4.5-1.fc43 | [FEDORA-2026-E8A6485109](https://patchblox.com/security/data/fix/linux/fedora-2026-e8a6485109.md) | Sep 10, 2026 | | Linux | dovecot23 sles 15.6 | 2.3.21.1-150200.76.1 | [SUSE-SU-2026:4139-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4139-1.md) | Sep 14, 2026 | | Linux | dovecot23 sles 15.7 | 2.3.21.1-150200.76.1 | [SUSE-SU-2026:4139-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-4139-1.md) | Sep 14, 2026 | | Linux | dovecot24 opensuse-leap 16.0 | 2.4.4-160000.2.1 | [OPENSUSE-SU-2026:21720-1](https://patchblox.com/security/data/fix/linux/opensuse-su-2026-21720-1.md) | Sep 1, 2026 | | Linux | dovecot24 sles 16.0 | 2.4.4-160000.2.1 | [SUSE-SU-2026:23595-1](https://patchblox.com/security/data/fix/linux/suse-su-2026-23595-1.md) | Sep 1, 2026 | --- Data as of 2026-11-08T00:53:09Z UTC. 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