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.
Metrics
Affected Vendors & Products
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References
History
Fri, 27 Mar 2026 10:00:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| Title | Dovecot OTP Replay Allows Unauthorized Authentication |
Fri, 27 Mar 2026 08:30:00 +0000
| Type | Values Removed | Values Added |
|---|---|---|
| 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. | |
| Weaknesses | CWE-294 | |
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| Metrics |
cvssV3_1
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MITRE
Status: PUBLISHED
Assigner: OX
Published:
Updated: 2026-03-27T12:33:26.733Z
Reserved: 2026-02-24T08:46:09.373Z
Link: CVE-2026-27855
Vulnrichment
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NVD
Status : Received
Published: 2026-03-27T09:16:19.610
Modified: 2026-03-27T09:16:19.610
Link: CVE-2026-27855
Redhat
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