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.
Affected products
| Vendor | Product | Affected | Fixed |
|---|---|---|---|
| Open-Xchange | OX Dovecot Pro | 2.3.0 – < 2.3.22.2, 3.0.0 – < 3.0.7, 3.1.0 – < 3.1.6 | 2.3.22.2 |
| Open-Xchange | OX Dovecot CE | 2.3.0 – < 2.4.5 | 2.4.5 |
Fixed in Linux distributions
Distributions backport fixes, so the version that fixes this vulnerability differs per release — upgrade to at least the version shown. From the distributions' security trackers and advisories.
Debian
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Debian 14 | dovecot | 1:2.4.5+dfsg1-1 | — |
| Debian 13 | dovecot | 1:2.4.1+dfsg1-6+deb13u7 | — |
| Debian 12 | dovecot | 1:2.3.19.1+dfsg1-2.1+deb12u7 | — |
Ubuntu
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 26.04 LTS | dovecot | No fix yet | — |
| Ubuntu 24.04 LTS | dovecot | No fix yet | — |
| Ubuntu 22.04 LTS | dovecot | No fix yet | — |
| Ubuntu 20.04 LTS | dovecot | No fix yet | — |
| Ubuntu 18.04 LTS | dovecot | No fix yet | — |
Show 2 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Ubuntu 16.04 LTS | dovecot | No fix yet | — |
| Ubuntu Pro 14.04 LTS | dovecot | No fix yet | — |
Red Hat
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| RHEL 10 | dovecot +4 | 1:2.3.21-19.el10_2.8 | RHSA-2026:79371 |
| RHEL 9 | dovecot +4 | 1:2.3.16-18.el9_8.8 | RHSA-2026:80825 |
| RHEL 8 | dovecot +4 | 1:2.3.16-16.el8_10 | RHSA-2026:76763 |
AlmaLinux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux 10 | dovecot +4 | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux 9 | dovecot +4 | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux 8 | dovecot +4 | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
Rocky Linux
Errata ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Rocky Linux 10 | dovecot | 1:2.3.21-19.el10_2.8 | RLSA-2026:79371 |
| Rocky Linux 9 | dovecot | 1:2.3.16-18.el9_8.8 | RLSA-2026:80825 |
| Rocky Linux 8 | dovecot | 1:2.3.16-16.el8_10 | RLSA-2026:76763 |
SUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES 15 SP7 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 15 SP6 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 15 SP5 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 15 SP4 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
Show 7 more (older releases, extended support, other products)Fewer releases
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| SLES for SAP 16.0 | dovecot24 | 2.4.4-160000.2.1 | SUSE-SU-2026:23595-1 |
| SLES for SAP 15 SP6 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES for SAP 15 SP5 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES for SAP 15 SP4 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLES 16.0 | dovecot24 | 2.4.4-160000.2.1 | SUSE-SU-2026:23595-1 |
| SLE HPC 15 SP5 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
| SLE HPC 15 SP4 | dovecot23 | 2.3.21.1-150200.76.1 | SUSE-SU-2026:4139-1 |
openSUSE
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| openSUSE Tumbleweed | dovecot24 | 2.4.5-1.1 | openSUSE-SU-2026:11629-1 |
| openSUSE Leap 16.0 | dovecot24 | 2.4.4-160000.2.1 | openSUSE-SU-2026:21720-1 |
Alpine
Security tracker ↗| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine v3.24 | dovecot | 2.4.5-r0 | — |
| Alpine v3.23 | dovecot | 2.4.5-r0 | — |
Azure Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Azure Linux 3 | dovecot | No fix yet | — |
Oracle Linux
| Release | Package | Fixed in | Advisory |
|---|---|---|---|
| Oracle Linux 10 | dovecot +4 | 1:2.3.21-19.el10_2.8 | ELSA-2026-79371 |
| Oracle Linux 9 | dovecot +4 | 1:2.3.16-18.el9_8.8 | ELSA-2026-80825 |
| Oracle Linux 8 | dovecot +4 | 1:2.3.16-16.el8_10 | ELSA-2026-76763 |
Advisories 17
- WID-SEC-2026-3076 Dovecot: Mehrere Schwachstellen BSI CERT-Bund (WID) · Nov 11, 2026
- ALSA-2026:80825 Important: dovecot security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:79371 Important: dovecot security update AlmaLinux Security Advisories · Oct 29, 2026
- ALSA-2026:76763 Important: dovecot security, bug fix, and enhancement update AlmaLinux Security Advisories · Oct 29, 2026
- RHSA-2026:80825 Red Hat Security Advisory: dovecot security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:79371 Red Hat Security Advisory: dovecot security update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RHSA-2026:76763 Red Hat Security Advisory: dovecot security, bug fix, and enhancement update Red Hat Security Advisories (RHSA) · Oct 14, 2026
- RLSA-2026:80825 Important: dovecot security update Rocky Linux Security Advisories · Oct 14, 2026
- ELSA-2026-80825 Important: dovecot security update (Oracle Linux 9) Oracle Linux Security Advisories (ELSA) · Oct 12, 2026
- RLSA-2026:79371 Important: dovecot security update Rocky Linux Security Advisories · Oct 10, 2026
- ELSA-2026-79371 Important: dovecot security update (Oracle Linux 10) Oracle Linux Security Advisories (ELSA) · Oct 8, 2026
- RLSA-2026:76763 Important: dovecot security, bug fix, and enhancement update Rocky Linux Security Advisories · Oct 7, 2026
- ELSA-2026-76763 Important: dovecot security, bug fix, and enhancement update (Oracle Linux 8) Oracle Linux Security Advisories (ELSA) · Oct 6, 2026
- SUSE-SU-2026:23595-1 Security update for dovecot24 SUSE / openSUSE Security Updates · Sep 29, 2026
- SUSE-SU-2026:4139-1 Security update for dovecot23 SUSE / openSUSE Security Updates · Sep 28, 2026
- openSUSE-SU-2026:21720-1 Security update for dovecot24 SUSE / openSUSE Security Updates · Sep 2, 2026
- openSUSE-SU-2026:11629-1 dovecot24-2.4.5-1.1 on GA media SUSE / openSUSE Security Updates · Aug 29, 2026