CVE-2026-104704 Progressive Robot hMailServer - Man-in-the-Middle

Progressive Robot hMailServer 6.0.0 through 6.3.5 contains a misconfiguration in TLS enforcement for outbound SMTP delivery caused by improper handling of DNSSEC-validated TLSA records, letting network attackers suppress STARTTLS and read or modify messages in cleartext, exploit requires active network position.

CVSS base score 7.4 /10
High
CISA KEV
Not listed
Public exploit
None known
EPSS
0.15% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Man-in-the-Middle
Impact
Information Disclosure, Data Tampering
CVSS vector
CVSS:3.1/AV:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:N
Published
8 October 2026
Updated
15 October 2026
Weakness
CWE-319

Vendor fix

Update to the latest version that properly enforces TLS for outbound SMTP delivery.

Patching closes this CVE. It does not tell you which of your systems run the affected version, or what else is exposed alongside them.

References

← All CVEs