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CVE-2026-27855

5.9 medium SSVC exploitation: none Analyzed
NVD · CVE.org

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.

Fix

Patch, vendor advisory and mitigation references on NVD 1

Every line above is quoted from NVD, CISA, Microsoft, the vendor's own advisory or DISA; nothing is generated.

Change history 1

  1. First seenCVSS 5.9 · dovecot, open-xchangeNVD modified 2026-10-26 22:10

Affected (CPE criteria) 2

  • cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:*
  • cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:*

References 1