CVE-2026-27859

Name	CVE-2026-27859
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.
Source	CVE (at NVD; CERT, ENISA, LWN, oss-sec, fulldisc, Debian ELTS, Red Hat, Ubuntu, Gentoo, SUSE bugzilla/CVE, GitHub advisories/code/issues, web search, more)

Vulnerable and fixed packages

The table below lists information on source packages.

Source Package	Release	Version	Status
dovecot (PTS)	bullseye	1:2.3.13+dfsg1-2+deb11u1	vulnerable
	bullseye (security)	1:2.3.13+dfsg1-2+deb11u2	vulnerable
	bookworm, bookworm (security)	1:2.3.19.1+dfsg1-2.1+deb12u1	vulnerable
	trixie	1:2.4.1+dfsg1-6+deb13u3	vulnerable
	trixie (security)	1:2.4.1+dfsg1-6+deb13u1	vulnerable
	forky, sid	1:2.4.2+dfsg1-4	vulnerable

The information below is based on the following data on fixed versions.

Package	Type	Release	Fixed Version	Urgency	Origin	Debian Bugs
dovecot	source	(unstable)	(unfixed)

Notes

https://documentation.open-xchange.com/dovecot/security/advisories/html/2026/oxdc-adv-2026-0001.html#cve-2026-27859-v3-0-2-regression-message-headers-mime-parameter-parsing-can-cause-excessive-cpu-usage