CVE-2026-103649 Progressive Robot hMailServer - Denial of Service

Progressive Robot hMailServer 6.3.0 through 6.3.5 Linux builds contain a denial of service caused by missing network timeouts in socket handling, letting remote attackers hold server threads indefinitely, exploit requires sending crafted mail to trigger outbound delivery to attacker-controlled domains.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
EPSS
0.27% 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-1088

Vendor fix

Update to a version later than 6.3.5 or the latest available version.

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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