CVE-2026-40016

Name	CVE-2026-40016
Description	Attacker can upload a malicious Sieve script over ManageSieve service (or locally) to bypass configured CPU time limits for Sieve up to 130 times of the configured limit. Attacker can use this to degrade server performance and bypass configured CPU time limits for Sieve scripts. Install fixed version, or alternatively prevent direct access to Sieve scripts via ManageSieve or local access. 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)
References	DSA-6313-1
Debian Bugs	1136444

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+deb11u3	vulnerable
	bookworm	1:2.3.19.1+dfsg1-2.1+deb12u5	vulnerable
	bookworm (security)	1:2.3.19.1+dfsg1-2.1+deb12u6	fixed
	trixie	1:2.4.1+dfsg1-6+deb13u5	vulnerable
	trixie (security)	1:2.4.1+dfsg1-6+deb13u6	fixed
	forky, sid	1:2.4.4+dfsg1-1	fixed

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

Package	Type	Release	Fixed Version	Origin	Debian Bugs
dovecot	source	bookworm	1:2.3.19.1+dfsg1-2.1+deb12u6	DSA-6313-1
dovecot	source	trixie	1:2.4.1+dfsg1-6+deb13u6	DSA-6313-1
dovecot	source	(unstable)	1:2.4.4+dfsg1-1		1136444

Notes

https://www.openwall.com/lists/oss-security/2026/05/12/6
Fixed by: https://github.com/dovecot/pigeonhole/commit/5b0ed9d1034c023d3daf218b6b8656f0cdd383dc (2.4.4)