Vulnerability · Published Aug 28, 2026 · Assigned by OX
CVE-2026-40019
Medium 5.9
In plain English
A medium-severity uncontrolled resource consumption in OX Dovecot CE from Open-Xchange GmbH. There are no confirmed reports of exploitation so far. The chance it is exploited in the next 30 days is estimated at 0.4% (higher than 31% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An unauthenticated attacker can send a truncated quoted argument to the ManageSieve login process, which makes it spin in an infinite loop consuming CPU. This can cause degradation or denial of service for Sieve script management, and repeated connections can consume all available CPU on the server. Monitor system for abnormal CPU usage and kill the offending process. Restrict network access to the ManageSieve service to trusted clients. Update to non-vulnerable version. No publicly available exploits are known.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| AlmaLinux:10 | dovecot | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-devel | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-devel | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-devel | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-mysql | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-mysql | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-mysql | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-pgsql | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-pgsql | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-pgsql | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| AlmaLinux:10 | dovecot-pigeonhole | 1:2.3.21-19.el10_2.8 | ALSA-2026:79371 |
| AlmaLinux:8 | dovecot-pigeonhole | 1:2.3.16-16.el8_10 | ALSA-2026:76763 |
| AlmaLinux:9 | dovecot-pigeonhole | 1:2.3.16-18.el9_8.8 | ALSA-2026:80825 |
| Alpine:v3.23 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-40019 |
| Alpine:v3.24 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-40019 |
| Debian:14 | dovecot | 1:2.4.5+dfsg1-1 | DEBIAN-CVE-2026-40019 |
| Rocky Linux:10 | dovecot | 1:2.3.21-19.el10_2.8 | RLSA-2026:79371 |
| Rocky Linux:8 | dovecot | 1:2.3.16-16.el8_10 | RLSA-2026:76763 |
| Rocky Linux:9 | dovecot | 1:2.3.16-18.el9_8.8 | RLSA-2026:80825 |
| Ubuntu:22.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-40019 |
| Ubuntu:24.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-40019 |
| Ubuntu:26.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-40019 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Open-Xchange GmbH | OX Dovecot CE | 2.4.3 – before 2.4.5 |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:N/I:N/A:H