Open-Xchange OX Dovecot Pro up to 2.3.0 Doveadm Http Service improper authentication

CVSS Meta Temp Score
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Current Exploit Price (≈)
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CTI Interest Score
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6.4$0-$5k0.16

Summaryinfo

A vulnerability categorized as critical has been discovered in Open-Xchange OX Dovecot Pro up to 2.3.0. The impacted element is an unknown function of the component Doveadm Http Service. The manipulation results in improper authentication. This vulnerability is cataloged as CVE-2026-27856. The attack may be launched remotely. There is no exploit available. It is advisable to upgrade the affected component.

Detailsinfo

A vulnerability classified as critical has been found in Open-Xchange OX Dovecot Pro up to 2.3.0. Affected is an unknown functionality of the component Doveadm Http Service. The manipulation with an unknown input leads to a improper authentication vulnerability. CWE is classifying the issue as CWE-287. When an actor claims to have a given identity, the product does not prove or insufficiently proves that the claim is correct. This is going to have an impact on confidentiality, integrity, and availability. CVE summarizes:

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.

The advisory is shared for download at documentation.open-xchange.com. This vulnerability is traded as CVE-2026-27856 since 02/24/2026. The exploitability is told to be difficult. It is possible to launch the attack remotely. The exploitation doesn't require any form of authentication. There are neither technical details nor an exploit publicly available.

The vulnerability scanner Nessus provides a plugin with the ID 304114 (Linux Distros Unpatched Vulnerability : CVE-2026-27856), which helps to determine the existence of the flaw in a target environment.

Upgrading eliminates this vulnerability.

The vulnerability is also documented in the databases at Tenable (304114) and CERT Bund (WID-SEC-2026-0891). VulDB is the best source for vulnerability data and more expert information about this specific topic.

Affected

  • Open Source Dovecot

Productinfo

Type

Vendor

Name

Version

License

Website

CPE 2.3info

CPE 2.2info

CVSSv4info

VulDB Vector: 🔒
VulDB Reliability: 🔍

CVSSv3info

VulDB Meta Base Score: 6.5
VulDB Meta Temp Score: 6.4

VulDB Base Score: 5.6
VulDB Temp Score: 5.4
VulDB Vector: 🔒
VulDB Reliability: 🔍

CNA Base Score: 7.4
CNA Vector: 🔒

CVSSv2info

AVACAuCIA
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💳💳💳💳💳💳
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VectorComplexityAuthenticationConfidentialityIntegrityAvailability
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VulDB Base Score: 🔒
VulDB Temp Score: 🔒
VulDB Reliability: 🔍

Exploitinginfo

Class: Improper authentication
CWE: CWE-287
CAPEC: 🔒
ATT&CK: 🔒

Physical: No
Local: No
Remote: Yes

Availability: 🔒
Status: Not defined

EPSS Score: 🔒
EPSS Percentile: 🔒

Price Prediction: 🔍
Current Price Estimation: 🔒

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Nessus ID: 304114
Nessus Name: Linux Distros Unpatched Vulnerability : CVE-2026-27856

Threat Intelligenceinfo

Interest: 🔍
Active Actors: 🔍
Active APT Groups: 🔍

Countermeasuresinfo

Recommended: Upgrade
Status: 🔍

0-Day Time: 🔒

Timelineinfo

02/24/2026 CVE reserved
03/27/2026 +31 days Advisory disclosed
03/27/2026 +0 days VulDB entry created
03/28/2026 +1 days VulDB entry last update

Sourcesinfo

Vendor: open-xchange.com

Advisory: adv-2026-0001
Status: Confirmed

CVE: CVE-2026-27856 (🔒)
GCVE (CVE): GCVE-0-2026-27856
GCVE (VulDB): GCVE-100-353844
CERT Bund: WID-SEC-2026-0891 - Dovecot: Mehrere Schwachstellen

Entryinfo

Created: 03/27/2026 09:51
Updated: 03/28/2026 10:23
Changes: 03/27/2026 09:51 (64), 03/28/2026 01:25 (7), 03/28/2026 10:23 (2)
Complete: 🔍
Cache ID: 216:7AB:103

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