CVE-2026-107584

Progressive Robot hMailServer 6.0.0 through 6.3.5 fails open when applying DANE (RFC 7672) to outbound SMTP delivery. The server's validating DNSSEC resolver treated a TLSA or MX lookup that did not complete (no answer, SERVFAIL, a malformed reply), an answer without the requested records and without an NSEC/NSEC3 proof of their absence, and an answer whose records carried no applicable RRSIG as if the recipient domain were unsigned, and from 6.2.19 it also delivered to mail exchangers taken from an unvalidated MX lookup that the DNSSEC-validated MX record set did not name. An attacker who can drop, forge or strip DNS answers on the path to the server's resolver, at the resolver, or between the resolver and the recipient domain's name servers, and who holds an active position on the SMTP path, can thereby disable DANE for a DNSSEC-signed recipient domain and cause messages to be delivered in cleartext or to a host of the attacker's choosing with an arbitrary certificate, where they can be read and modified.

CVSS v3 7.4 HIGH

7.4^/10

CVSS v3 : HIGH

Vector :

Exploitability : 2.2 / Impact : 5.2

Attack Vector NETWORK

Attack Complexity HIGH

Privileges Required NONE

User Interaction NONE

Confidentiality Impact HIGH

Integrity Impact HIGH

Availability Impact NONE

Scope UNCHANGED

References

Link	Resource
https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6
https://gitlab.com/hmailserver/hmailserver/-/work_items/64

Configurations

No configuration.

History

08 Oct 2026, 12:17

Type	Values Removed	Values Added
New CVE

Information

Published : 2026-10-08 12:17

Updated : 2026-10-08 21:02

NVD link : CVE-2026-107584

Mitre link : CVE-2026-107584

CVE.ORG link : CVE-2026-107584

JSON object : View

Products Affected

No product.

CWE

CWE-636

Not Failing Securely ('Failing Open')

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