CVE-2026-27855

medium

Published 2026-03-27 · Modified 2026-04-29

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CVSS v3

5.9

CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:N/A:N

CVSS v4 NEW

—

not yet in upstream

VIR risk

5.9

Description

Dovecot OTP authentication is vulnerable to replay attack under specific conditions. If auth cache is enabled, and username is altered in passdb, then OTP credentials can be cached so that same OTP reply is valid. An attacker able to observe an OTP exchange is able to log in as the user. If authentication happens over unsecure connection, switch to SCRAM protocol. Alternatively ensure the communcations are secured, and if possible switch to OAUTH2 or SCRAM. No publicly available exploits are known.

Predictions

Exploit likelihood

69%

Patch ETA

—

Heuristic predictions, AS-IS, for prioritization only.

Mitigations

No mitigations published for this CVE yet.

The vendor-content worker queues fetches as references arrive (check back in a few minutes). Or — if you've already worked around this in production — publish your fix to the community-verified tier.

✚ Propose a mitigation on Community → Mitigations published via the community go through AI scoring + 2 human reviewers + 7-day silent objection window before landing here with source_tier=community-verified.

OS impact

OS	Version	Status	Fixed in
debian	bookworm	fixed	`1:2.3.19.1+dfsg1-2.1+deb12u2`
debian	bullseye	fixed	`1:2.3.13+dfsg1-2+deb11u3`
debian	forky	fixed	`1:2.4.3+dfsg1-1`
debian	sid	fixed	`1:2.4.3+dfsg1-1`
debian	trixie	fixed	`1:2.4.1+dfsg1-6+deb13u4`
sles		affected

Application impact

Vendor	Product	Versions	Fixed
dovecot	dovecot	`{"endExcluding":"2.4.3"}`	`2.4.3`
open-xchange	dovecot	`{"endIncluding":"2.3.0"}`

References

CWEs

CWE-294

Community-verified mitigations for this CVE will appear above when contributors publish them.

Verify integrity in audit chain (admin only). AS-IS.