Improper authentication in Open-Xchange GmbH OX Dovecot Pro
Priority LOW 35CWE-287Published · Updated
Key facts
- Attack vector
- Network
- Privileges required
- None
- User interaction
- None
- Attack complexity
- High
- Impact type
- Security bypass
- Confidentiality · integrity · availability
- High · High · None
- Fix status
- Partial Red Hat: 2 fixed, 1 without a fix
Attack profile from CVSS 3.1 · CNA. Fix status from CNA and Red Hat. Impact type from CWE-287.
Summary
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.
Why it matters now
Exploitation None reported CISA SSVC · not in CISA KEV
EPSS 0.00399 34th percentileScored 2026-11-07
Fix Partial Red Hat: 1 advisoryRed Hat: 2 fixed, 1 without a fix
SSVC decision points
CISA ADP · SSVC 2.0.3
- Exploitation
- None
- Automatable
- No
- Technical impact
- Total
The decision (Track, Attend, Act) also depends on your mission and well-being impact; see CISA's SSVC guide.
Affected products
| Vendor | Product | Affected versions | Fixed in | Status | Source |
|---|---|---|---|---|---|
| Open-Xchange GmbH | OX Dovecot Pro | up to 2.3.0 | — | No fix listed | CNA |
- OX Dovecot Pro VendorOpen-Xchange GmbH Affected up to 2.3.0 Fixed in — No fix listed CNA
CPE configurations NVD · 2
| CPE | Versions | Role | Vendor |
|---|---|---|---|
| cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:* | before 2.4.3 | Vulnerable | The Dovecot Project |
| cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* | before 2.3.22.1; 3.0.0 to before 3.0.5; 3.1.0 to before 3.1.4 | Vulnerable | Open-Xchange GmbH |
- cpe:2.3:a:dovecot:dovecot:*:*:*:*:*:*:*:* Versions before 2.4.3 Vulnerable ·The Dovecot Project
- cpe:2.3:a:open-xchange:dovecot:*:*:*:*:pro:*:*:* Versions before 2.3.22.1; 3.0.0 to before 3.0.5; 3.1.0 to before 3.1.4 Vulnerable ·Open-Xchange GmbH
Remediation
Red Hat 1 advisory
- RHSA-2026:26564 Released 2026-06-17 · Red Hat rating Importantdovecot security update
- Red Hat Enterprise Linux Server (v. 7 ELS) dovecot-1:2.2.36-8.el7_9.1, dovecot-1:2.2.36-8.el7_9.1.ppc, dovecot-mysql-1:2.2.36-8.el7_9.1 +2
- Red Hat Enterprise Linux Server Optional (v. 7 ELS) dovecot-devel-1:2.2.36-8.el7_9.1
Vendor assessments
Red Hat
Red Hat rating: Important. Red Hat's page for this CVE →
| Product | Status | Plan or fix |
|---|---|---|
| Red Hat Enterprise Linux 6 | Affected | No fix yet |
| Red Hat Enterprise Linux Server (v. 7 ELS) | Fixed | RHSA-2026:26564 |
| Red Hat Enterprise Linux Server Optional (v. 7 ELS) | Fixed | RHSA-2026:26564 |
Not affected: 3 products
- Red Hat Enterprise Linux 10
- Red Hat Enterprise Linux 8
- Red Hat Enterprise Linux 9
Timeline
- 2026-10-02 Threatist record created from CVE-2026-27856
- 2026-10-03 Alias added: GHSA-mv3x-9fw3-qf38
References
More Open-Xchange GmbH Dovecot vulnerabilities
- TI-2026-22201 When safe filter is used with variable expansion, all following pipelines on the same… CVSS 3.1CRITICAL 9.1
- TI-2026-22208 Uncontrolled resource consumption in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.5
- TI-2025-36674 Improper input validation in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.5
- TI-2025-36670 Improper input validation in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.5
- TI-2026-19360 SQL injection in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 8.2
- TI-2026-22207 Uncontrolled resource consumption in Open-Xchange GmbH OX Dovecot Pro CVSS 3.1HIGH 7.5
Sources
- CVE-2026-27856 · CVE Program
- CVE-2026-27856 · NVD
- FIRST EPSS
- GHSA-mv3x-9fw3-qf38 · GitHub Advisory Database · CC BY 4.0
- CVE-2026-27856 · Red Hat security data · CC BY 4.0
This product uses the NVD API but is not endorsed or certified by the NVD. Sources and licences