CVE-2026-107569 Progressive Robot hMailServer - Denial of Service

Progressive Robot hMailServer 6.0.0 through 6.3.6 contains a denial of service caused by improper validation of the X-hMailServer-LoopCount header in mail forwarding logic, letting remote unauthenticated attackers stop mail service by triggering infinite mail loops, exploit requires sending crafted emails with manipulated LoopCount header.

CVSS base score 7.5 /10
High
CISA KEV
Not listed
Public exploit
None known
Authentication
Not required
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
19 October 2026
Updated
20 October 2026
Weakness
CWE-606

Vendor fix

Update to a version later than 6.3.6 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

← All CVEs