Vulnerability · Published Mar 27, 2026 · Assigned by OX
CVE-2026-27859
Medium 5.3
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 0.4% (higher than 32% of all known vulnerabilities). Fixed versions are available - upgrade the affected package.
Official description
A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably formatted mail message causes mail delivery process to consume large amounts of CPU time. Use MTA capabilities to limit RFC 2231 MIME parameters in mail messages, or upgrade to fixed version where the processing is limited. No publicly available exploits are known.
Affected packages & fixed versions
| Ecosystem | Package | Fixed in | Advisory |
|---|---|---|---|
| Alpine:v3.23 | dovecot | 2.4.3-r0 | ALPINE-CVE-2026-27859 |
| Alpine:v3.24 | dovecot | 2.4.3-r0 | ALPINE-CVE-2026-27859 |
| Debian:12 | dovecot | 1:2.3.19.1+dfsg1-2.1+deb12u2 | DEBIAN-CVE-2026-27859 |
| Debian:13 | dovecot | 1:2.4.1+dfsg1-6+deb13u4 | DEBIAN-CVE-2026-27859 |
| Debian:14 | dovecot | 1:2.4.3+dfsg1-1 | DEBIAN-CVE-2026-27859 |
| Ubuntu:22.04:LTS | dovecot | 1:2.3.16+dfsg1-3ubuntu2.7 | UBUNTU-CVE-2026-27859 |
| Ubuntu:24.04:LTS | dovecot | 1:2.3.21+dfsg1-2ubuntu6.3 | UBUNTU-CVE-2026-27859 |
| Ubuntu:25.10 | dovecot | 1:2.4.1+dfsg1-5ubuntu4.1 | UBUNTU-CVE-2026-27859 |
Affected products (as reported)
| Vendor | Product | Versions |
|---|---|---|
| Open-Xchange GmbH | OX Dovecot Pro | 0 – through 3.0.20 – through 3.1.00 – through 2.4.0 |
Weakness: CWE-400 · Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L