# CVE-2026-27859: A mail message containing excessive amount of RFC 2231 MIME parameters causes LMTP to use too much CPU. A suitably…

Source: https://junglewise.ai/threats/cve-2026-27859-a-mail-message-containing-excessive-amount-of-rfc-2231-mime  
Publisher: Junglewise Threat Intelligence, https://junglewise.ai/threats  
Published: 2026-03-27  
License: CC BY 4.0 with a link back

CVE-2026-27859 · Severity: medium · CVSS 5.3 · Published 2026-03-27

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.

Technologies: [Dovecot](https://junglewise.ai/threats/technologies/dovecot), [Open-Xchange Dovecot](https://junglewise.ai/threats/technologies/open-xchange-dovecot). Vendors: [Dovecot](https://junglewise.ai/threats/vendors/dovecot), [Open-Xchange](https://junglewise.ai/threats/vendors/open-xchange).

## Quick answers

**Is CVE-2026-27859 exploited in the wild?** No. Junglewise Threat Intelligence has no report of CVE-2026-27859 being exploited in the wild.

**How severe is CVE-2026-27859?** Medium severity, with a CVSS score of 5.3, published 27 March 2026.

**Which products and versions are affected?** Dovecot, Open-Xchange Dovecot. The advisory does not name versions.

**Is there a fix for CVE-2026-27859?** No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.

**Am I affected by CVE-2026-27859?** Check whether you run Dovecot or Open-Xchange Dovecot. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.

## Affected products

- Dovecot
- Open-Xchange Dovecot

## Related threats

- [Dovecot ManageSieve denial of service via malformed pre-auth command](https://junglewise.ai/threats/cve-2026-33605-dovecot-managesieve-denial-of-service-via-malformed-pre-auth)
- [Open-Xchange Dovecot uncontrolled memory consumption in IMAP](https://junglewise.ai/threats/cve-2026-42006-open-xchange-dovecot-uncontrolled-memory-consumption-in-imap)
- [Open-Xchange Dovecot improper access control in IMAP SETACL](https://junglewise.ai/threats/cve-2026-40020-open-xchange-dovecot-improper-access-control-in-imap-setacl)
- [Open-Xchange Dovecot CPU limit bypass in Sieve scripts](https://junglewise.ai/threats/cve-2026-40016-open-xchange-dovecot-cpu-limit-bypass-in-sieve-scripts)
- [Open-Xchange Dovecot SCRAM TLS channel binding spoofing](https://junglewise.ai/threats/cve-2026-33603-open-xchange-dovecot-scram-tls-channel-binding-spoofing)