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Dovecot OTP authentication is vulnerable to replay attack under specific conditions. If auth cache is enabled, and username is altered in passdb, then...
CVE-2026-27855
First seen on SecPulse
Fix status by distribution
Fixed packages published by each distribution for this CVE
- Alpine Linux ALPINE-CVE-2026-27855 dovecot Fixed in: 2.4.3-r0
- Debian DEBIAN-CVE-2026-27855 dovecot Fixed in: 1:2.3.13+dfsg1-2+deb11u3
Original description The description as published by the source.
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.
References
- advisory documentation.open-xchange.com
- advisory github.com
- advisory nvd.nist.gov