CVE-2026-107576 Progressive Robot hMailServer - Denial of Service

Progressive Robot hMailServer 6.0.0 through 6.3.5 contains a denial of service vulnerability caused by inefficient algorithmic complexity in inbound DKIM and ARC signature verification, letting remote unauthenticated attackers make mail services unavailable by sending crafted messages.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.43% chance of exploitation in 30 days
View the NVD record ↗

Details

Type
Denial of Service
Impact
Denial Of Service
CVSS vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
Published
8 October 2026
Updated
15 October 2026
Weakness
CWE-407

Vendor fix

Update to the latest version beyond 6.3.5.

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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