Vulnerability · Published Aug 28, 2026 · Assigned by OX
CVE-2026-27852
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 37% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
An attacker that can send mail to a user can craft a message whose headers contain a very large number of email addresses or MIME parameters, which causes excessive memory usage when the message is later parsed. The message is still delivered, but reading it over IMAP can exhaust the memory limit of the process and terminate it, causing denial of service for the affected user. 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-2026-27852 |
| Alpine:v3.24 | dovecot | 2.4.5-r0 | ALPINE-CVE-2026-27852 |
| Debian:12 | dovecot | 1:2.3.19.1+dfsg1-2.1+deb12u7 | DEBIAN-CVE-2026-27852 |
| Debian:13 | dovecot | 1:2.4.1+dfsg1-6+deb13u7 | DEBIAN-CVE-2026-27852 |
| Debian:14 | dovecot | 1:2.4.5+dfsg1-1 | DEBIAN-CVE-2026-27852 |
| 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-2026-27852 |
| Ubuntu:24.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-27852 |
| Ubuntu:26.04:LTS | dovecot | no fix listed | UBUNTU-CVE-2026-27852 |
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