CVE-2026-27855
Publication date 27 March 2026
Last updated 1 April 2026
Ubuntu priority
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.
Status
| Package | Ubuntu Release | Status |
|---|---|---|
| dovecot | 25.10 questing |
Fixed 1:2.4.1+dfsg1-5ubuntu4.1
|
| 24.04 LTS noble |
Fixed 1:2.3.21+dfsg1-2ubuntu6.3
|
|
| 22.04 LTS jammy |
Fixed 1:2.3.16+dfsg1-3ubuntu2.7
|
|
| 20.04 LTS focal |
Vulnerable
|
|
| 18.04 LTS bionic |
Vulnerable
|
|
| 16.04 LTS xenial |
Vulnerable
|
|
| 14.04 LTS trusty |
Vulnerable
|
Severity score breakdown
| Parameter | Value |
|---|---|
| Base score |
6.8 · Medium
|
| Attack vector | Network |
| Attack complexity | High |
| Privileges required | None |
| User interaction | Required |
| Scope | Unchanged |
| Confidentiality | High |
| Integrity impact | High |
| Availability impact | None |
| Vector | CVSS:3.1/AV:N/AC:H/PR:N/UI:R/S:U/C:H/I:H/A:N |
References
Related Ubuntu Security Notices (USN)
- USN-8136-1
- Dovecot vulnerabilities
- 31 March 2026