CVE-2026-27859

Name: CVE-2026-27859
Creator: NVD / NIST
Published: 2026-03-27T09:16:20.223+00:00
License: https://creativecommons.org/publicdomain/zero/1.0/

MEDIUMCVSS 5.3/10EPSS 0.37%

Last modified Jun 17, 2026

CVE-2026-27859 is a medium-severity vulnerability rated 5.3/10 on the CVSS scale. 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. EPSS estimates a 0.37% chance of exploitation in the next 30 days.

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.

Metrics

CVSS 3.1

5.3/10

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:L

EPSS Probability

0.37%

29.3th percentile

Probability of exploitation in the next 30 days. Learn more

Weakness Enumeration

CWE-400

Affected Software

Vendor	Product	Versions
Dovecot	Dovecot	< 2.4.3
Open-Xchange	Dovecot	< 3.0.5
Open-Xchange	Dovecot	>= 3.1.0, < 3.1.4

References

https://documentation.open-xchange.com/dovecot/security/advisories/csaf/2026/oxdc-adv-2026-0001.jsonVendor Advisory

Timeline

Published: Mar 27, 2026
Last Modified: Jun 17, 2026
Status: Analyzed

Frequently Asked Questions

What is CVE-2026-27859?

How severe is CVE-2026-27859?

CVE-2026-27859 has a CVSS score of 5.3/10 (MEDIUM severity). The EPSS model estimates a 0.37% probability of exploitation in the next 30 days.

How do I fix CVE-2026-27859?

Check the vendor references and advisories linked above for patched versions and mitigation guidance. You can also run a Strix scan to test if your systems are affected.

Are you affected by CVE-2026-27859?

Run a free Strix scan to check your systems for this vulnerability.

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Source: NVD / NIST