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Vulnerability · Published Mar 27, 2026 · Assigned by OX

CVE-2026-27857

Medium 4.3

In plain English

A medium-severity uncontrolled resource consumption in OX Dovecot Pro 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 0.7% (higher than 53% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.

Severity (CVSS 3.1)4.3Medium
Exploit odds (30 days)0.7%top 47.5% of all CVEs
Exploited in the wildNo reportsCISA SSVC: none
Attack toolingNoneno public tooling known

Official description

Sending "NOOP (((...)))" command with 4000 parenthesis open+close results in ~1MB extra memory usage. Longer commands will result in client disconnection. This 1 MB can be left allocated for longer time periods by not sending the command ending LF. So attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Attacker could connect possibly from even a single IP and create 1000 connections to allocate 1 GB of memory, which would likely result in reaching VSZ limit and killing the process and its other proxied connections. Install fixed version, there is no other remediation. No publicly available exploits are known.

Affected packages & fixed versions

EcosystemPackageFixed inAdvisory
AlmaLinux:10dovecot1:2.3.21-16.el10_1.1ALSA-2026:13498
AlmaLinux:10dovecot1:2.3.21-19.el10_2ALSA-2026:19149
AlmaLinux:8dovecot1:2.3.16-7.el8_10ALSA-2026:13830
AlmaLinux:9dovecot1:2.3.16-15.el9_7.1ALSA-2026:13857
AlmaLinux:9dovecot1:2.3.16-18.el9_8ALSA-2026:19364
AlmaLinux:10dovecot-devel1:2.3.21-19.el10_2ALSA-2026:19149
AlmaLinux:10dovecot-devel1:2.3.21-16.el10_1.1ALSA-2026:13498
AlmaLinux:8dovecot-devel1:2.3.16-7.el8_10ALSA-2026:13830
AlmaLinux:9dovecot-devel1:2.3.16-18.el9_8ALSA-2026:19364
AlmaLinux:9dovecot-devel1:2.3.16-15.el9_7.1ALSA-2026:13857
AlmaLinux:10dovecot-mysql1:2.3.21-19.el10_2ALSA-2026:19149
AlmaLinux:10dovecot-mysql1:2.3.21-16.el10_1.1ALSA-2026:13498
AlmaLinux:8dovecot-mysql1:2.3.16-7.el8_10ALSA-2026:13830
AlmaLinux:9dovecot-mysql1:2.3.16-15.el9_7.1ALSA-2026:13857
AlmaLinux:9dovecot-mysql1:2.3.16-18.el9_8ALSA-2026:19364
AlmaLinux:10dovecot-pgsql1:2.3.21-16.el10_1.1ALSA-2026:13498
AlmaLinux:10dovecot-pgsql1:2.3.21-19.el10_2ALSA-2026:19149
AlmaLinux:8dovecot-pgsql1:2.3.16-7.el8_10ALSA-2026:13830
AlmaLinux:9dovecot-pgsql1:2.3.16-15.el9_7.1ALSA-2026:13857
AlmaLinux:9dovecot-pgsql1:2.3.16-18.el9_8ALSA-2026:19364
AlmaLinux:10dovecot-pigeonhole1:2.3.21-19.el10_2ALSA-2026:19149
AlmaLinux:10dovecot-pigeonhole1:2.3.21-16.el10_1.1ALSA-2026:13498
AlmaLinux:8dovecot-pigeonhole1:2.3.16-7.el8_10ALSA-2026:13830
AlmaLinux:9dovecot-pigeonhole1:2.3.16-15.el9_7.1ALSA-2026:13857
AlmaLinux:9dovecot-pigeonhole1:2.3.16-18.el9_8ALSA-2026:19364
Alpine:v3.23dovecot2.4.3-r0ALPINE-CVE-2026-27857
Alpine:v3.24dovecot2.4.3-r0ALPINE-CVE-2026-27857
Debian:12dovecot1:2.3.19.1+dfsg1-2.1+deb12u2DEBIAN-CVE-2026-27857
Debian:13dovecot1:2.4.1+dfsg1-6+deb13u4DEBIAN-CVE-2026-27857
Debian:14dovecot1:2.4.3+dfsg1-1DEBIAN-CVE-2026-27857
Rocky Linux:10dovecot1:2.3.21-19.el10_2RLSA-2026:19149
Rocky Linux:10dovecot1:2.3.21-16.el10_1.1RLSA-2026:13498
Rocky Linux:8dovecot1:2.3.16-7.el8_10RLSA-2026:13830
Rocky Linux:9dovecot1:2.3.16-18.el9_8RLSA-2026:19364
Rocky Linux:9dovecot1:2.3.16-15.el9_7.1RLSA-2026:13857
Ubuntu:22.04:LTSdovecot1:2.3.16+dfsg1-3ubuntu2.7UBUNTU-CVE-2026-27857
Ubuntu:24.04:LTSdovecot1:2.3.21+dfsg1-2ubuntu6.3UBUNTU-CVE-2026-27857
Ubuntu:25.10dovecot1:2.4.1+dfsg1-5ubuntu4.1UBUNTU-CVE-2026-27857

Affected products (as reported)

VendorProductVersions
Open-Xchange GmbH OX Dovecot Pro 0 – through 2.3.0

Weakness: CWE-400, CWE-770 · Vector: CVSS:3.1/AV:N/AC:L/PR:L/UI:N/S:U/C:N/I:N/A:L

References