CVE-2026-27856

Name	CVE-2026-27856
Description	Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Figuring out the credential will lead into full access to the affected component. Limit access to the doveadm http service port, 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-2026-27856-doveadm-credentials-verified-without-timing-safety