Vulnerability · Published Aug 28, 2026 · Assigned by OX
CVE-2026-33605
High 7.5
In plain English
A high-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 39% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An unauthenticated attacker can crash the ManageSieve login process by sending a small malformed command before authenticating. If running in high-security mode (default for community releases), only the attacker's own connection is terminated. If running in high-performance mode (default for Pro releases), all connections handled by the same managesieve-login process are terminated. Repeating the attack can cause denial of service for Sieve script management. 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-2026-33605 |
| Alpine:v3.24 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-33605 |
| Debian:12 | dovecot | 1:2.3.19.1+dfsg1-2.1+deb12u7 | DEBIAN-CVE-2026-33605 |
| Debian:13 | dovecot | 1:2.4.1+dfsg1-6+deb13u7 | DEBIAN-CVE-2026-33605 |
| Debian:14 | dovecot | 1:2.4.5+dfsg1-1 | DEBIAN-CVE-2026-33605 |
| 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-2026-33605 |
| Ubuntu:24.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-33605 |
| Ubuntu:26.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-33605 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Open-Xchange GmbH | OX Dovecot Pro | 2.3.0 – before 2.3.22.23.0.0 – before 3.0.73.1.0 – before 3.1.6 |
| Open-Xchange GmbH | OX Dovecot CE | 2.3.0 – before 2.4.5 |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H