CVE-2026-27858

Name	CVE-2026-27858
Description	Attacker can send a specifically crafted message before authentication that causes managesieve to allocate large amount of memory. Attacker can force managesieve-login to be unavailable by repeatedly crashing the process. Protect access to managesieve protocol, or install fixed version. 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-2026-27858-managesieve-login-out-of-memory-dos