CVE-2026-27855
dovecot: Dovecot: Replay attack allows unauthorized login via observed One-Time Password (OTP) exchange
Severity
ModerateRed Hat Product Security
CVSS 3.1
Review impact separately from score.
Published · March 27, 2026
Updated · June 30, 2026
Description
A flaw was found in Dovecot. Under specific conditions, if the authentication cache is enabled and the username is altered in the password database, Dovecot's One-Time Password (OTP) authentication is vulnerable to a replay attack. A remote attacker able to observe an OTP exchange can exploit this flaw to log in as the legitimate user, leading to unauthorized access.
CVSS score applicability
The CVSS score(s) listed for this vulnerability do not reflect the associated product's status, and are included for informational purposes to better understand the severity of this vulnerability.
Mitigation
No mitigation is specified in collected source.
CVSS / CWE
CVSS 3.1 · 6.8CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N
CWE-294 · Authentication Bypass by Capture-replay