Improper Authentication in Dovecot and OX Dovecot Pro - CVE-2026-27856
Published: April 1, 2026 / Updated: April 1, 2026
Vulnerability identifier: #VU124730
CSH Severity: High
CVSS v4.0: CVSS:4.0/AV:N/AC:L/AT:P/PR:N/UI:N/VC:H/VI:H/VA:N/SC:N/SI:N/SA:N/E:U/U:Amber
CVE-ID: CVE-2026-27856
CWE-ID: CWE-287
Exploitation vector: Remote access
Exploit availability:
No public exploit available
Vendor: Dovecot
Affected software:
Dovecot
OX Dovecot Pro
Dovecot
OX Dovecot Pro
Detailed vulnerability description
The vulnerability allows a remote attacker to bypass authentication.
The vulnerability exists due to improper authentication in doveadm credentials verification when comparing provided credentials. A remote attacker can perform timing oracle attack to bypass authentication.
How to mitigate CVE-2026-27856
Install security update from vendor's website.