CVSS 3.1
7.0 highCVSS:3.1/AV:L/AC:H/PR:L/UI:N/S:U/C:H/I:H/A:HCVE-2026-126611 Improper Certificate Validation in hMailServer
High (7.0) in progressive robot ltd hmailserver. EPSS 0.08% estimated probability of exploitation activity in the next 30 days.
On this page
Progressive Robot hMailServer 6.3.4 through 6.3.7, with a MySQL or MariaDB database, TlsMode=verify-full and no TlsCaFile, does not verify the database server's certificate's issuer or name when the connection is one that MariaDB Connector/C treats as local - Server= set to 127.0.0.1, ::1 or localhost (on Linux a Unix socket), to . on Windows (a named pipe), or to a comma-separated list of servers that holds such an element - which allows a local attacker who can stand in for the database server, for example by listening on its port while it is stopped or restarting, to receive the database sign-in, the password included, and to read and modify the traffic between hMailServer and its database. hMailServer applied verify-full by turning the client's certificate verification on without a CA file, but MariaDB Connector/C 3.4.1 and later, on a connection they treat as local and with no CA file, accept any certificate within its validity period that is self-signed or sent with its own root, for any name (Connector/C 3.4.2 to 3.4.10 also one whose issuer they cannot find), so the client accepted the certificate an impostor made, asked no proof of the password and allowed a switch to an authentication method that sends the password unhashed, while hmailserver --check-database said the certificate had been checked against the system's trust store and the application log that it had been checked. The Windows builds bundle Connector/C 3.4.9 (6.3.4 to 6.3.6) and 3.4.11 (6.3.7); on Linux the distribution's client is used, and Connector/C 3.3 and 3.4.0 and Oracle's MySQL client are not affected. The configuration is not the default: TlsMode defaults to prefer, which checks no certificate.
Severity
- EPSS
- 0.08% estimated probability of exploitation activity in the next 30 days; 0th percentile. Scored 2026-11-13. A forecast for this CVE across the internet, not for your own systems.
- CWE
- CWE-295 Improper Certificate Validation
- OWASP Top 10
- A07:2025 Authentication Failures
- Published
- Modified
- Assigned by
- GitLab (CNA)
- NVD analysis
- Deferred: the NVD does not plan to analyze it
- Record from
- the NVD, synced
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Affected
- progressive robot ltd:hmailserver
Versions
From the CNA's record in the CVE List.
| Product | Affected |
|---|---|
| Progressive Robot Ltd hMailServer | from 6.3.4 through 6.3.7 |
Attack patterns (CAPEC)
- CAPEC-459 Creating a Rogue Certification Authority Certificate Likelihood: Medium · Severity: Very High
- CAPEC-475 Signature Spoofing by Improper Validation Likelihood: Low · Severity: High
The attack patterns MITRE's CAPEC relates to this record's weaknesses, as MITRE names them. Credits.
History
- The NVD deferred its analysis
Changes since this site first stored the record. The same for every record: /api/public/changes.