PT-2026-28363 · Dovecot+2 · Dovecot+2

Hamizanazman · Published 2026-01-01 · Updated 2026-04-16 · CVE-2026-27855

Positive Technologies (AI Summary)

CVSS v3.1

6.8

Medium

Base vector

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

Name of the Vulnerable Software and Affected Versions Dovecot versions prior to 2.4.3

Description Dovecot OTP authentication is susceptible to a replay attack under certain conditions. Specifically, if the authentication cache is enabled and a username is modified within the passdb, OTP credentials can be cached, allowing the same OTP reply to be valid for subsequent login attempts. An attacker observing an OTP exchange could potentially log in as the user. The issue occurs when authentication happens over an unsecure connection.

Recommendations Update to version 2.4.3 or later. If updating is not immediately possible, switch to the SCRAM protocol. Ensure communications are secured. If possible, switch to OAUTH2 or SCRAM.

Fix

Weakness Enumeration

CWE-294

Related Identifiers

CVE-2026-27855

OESA-2026-1849

OPENSUSE-SU-2026:10442-1

OPENSUSE-SU-2026:20554-1

SUSE-SU-2026:21208-1

USN-8136-1

Affected Products

Dovecot

Linuxmint

Ubuntu

References · 55

• https://osv.dev/vulnerability/OESA-2026-1849 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-27856 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-27857 · Security Note
• https://osv.dev/vulnerability/openSUSE-SU-2026:10442-1 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2025-59031 · Security Note
• https://ubuntu.com/security/CVE-2026-27858 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-27859 · Vendor Advisory
• https://ubuntu.com/security/CVE-2025-59028 · Vendor Advisory
• https://osv.dev/vulnerability/SUSE-SU-2026:21208-1 · Vendor Advisory
• https://osv.dev/vulnerability/ALPINE-CVE-2026-27855 · Vendor Advisory
• https://ubuntu.com/security/CVE-2026-27855 · Vendor Advisory
• https://security-tracker.debian.org/tracker/CVE-2026-27855 · Vendor Advisory
• https://ubuntu.com/security/CVE-2025-59031 · Vendor Advisory
• https://nvd.nist.gov/vuln/detail/CVE-2026-27855 · Security Note
• https://cve.org/CVERecord?id=CVE-2026-27855 · Security Note