CVE-2026-107567 Progressive Robot hMailServer - Authentication Bypass

Progressive Robot hMailServer 6.0.0 through 6.3.6 contains a broken authentication caused by DKIM signing messages based solely on the From header without sender authentication, letting remote unauthenticated attackers forge signed emails for hosted domains, exploit requires DKIM signing enabled and mail forwarding to external addresses.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
View the NVD record ↗

Details

Type
Authentication Bypass
Impact
Broken Authentication
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:H/A:N
Published
19 October 2026
Updated
20 October 2026
Weakness
CWE-348

Vendor fix

Update to a version later than 6.3.6 or apply patches that enforce sender authentication before DKIM signing.

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

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