CVE-2026-27856 Details
Description
Doveadm credentials are verified using direct comparison which is susceptible to timing oracle attack. An attacker can use this to determine the configured credentials. Figuring out the credential will lead into full access to the affected component. Limit access to the doveadm http service port, install fixed version. No publicly available exploits are known.
A vulnerability exists in Open-Xchange Dovecot Pro and Community Edition, specifically in versions 2.3.0, 2.3.22.1, 3.0.2, 3.0.5, 3.1.0, and 2.4.0. The issue arises because doveadm credentials are verified through direct comparison, creating a timing oracle vulnerability. This flaw allows an attacker to deduce the configured credentials, potentially leading to full access to the affected component. The vulnerability can be exploited by sending crafted authentication data that takes advantage of the timing discrepancy in the credential verification process.
Users are advised to limit access to the doveadm HTTP service port and to upgrade to a fixed version. The specific versions to upgrade to are Open-Xchange Dovecot Pro 3.1.4 or Open-Xchange Dovecot Community Edition 2.4.3.
Metrics
CVSS 4.0 Severity and Vector Strings:
No CVSS 4.0 data is available for this CVE.
CVSS 3.x Severity and Vector Strings:
No data available for CVSS Version 2.0 on this CVE.
CISA-ADP
Assessed Mar 27, 2026References to Advisories, Solutions, and Tools
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Weakness Enumeration
| CWE-ID | CWE Name | Source |
|---|---|---|
| NVD-CWE-Other | Weakness Not in a Standard CWE Category | [email protected] |
| CWE-208 | Observable Timing Discrepancy | redhat-SADP |
| CWE-287 | Improper Authentication | [email protected] |
Affected Products
| Product | Versions |
|---|---|
| dovecot dovecot | < 2.4.3 |
CPE
Remediation
| |
| open-xchange dovecot | < 2.3.22.1 >= 3.0.0, < 3.0.5 >= 3.1.0, < 3.1.4 |
CPE
Remediation
| |
Change History
6 change records found show changes
| Date | Action | Recorded By |
|---|---|---|
| Jul 15, 2026 | CVE Modified | redhat-SADP |
| Jun 30, 2026 | CVE Modified | redhat-SADP |
| Jun 17, 2026 | CVE Modified | [email protected] |
| Jun 17, 2026 | CVE Modified | CISA-ADP |
| Apr 29, 2026 | Initial Analysis | [email protected] |
| Mar 27, 2026 | New CVE Received | [email protected] |