---
title: "CVE-2026-104660: Progressive Robot hMailServer - Broken Access Control"
description: "Progressive Robot hMailServer 6.0.0 through 6.3.5 on Windows contains a broken access control vulnerability caused by missing authorization on COM objects, letting local users read/write arbitrary files and send mail as any sender without credentials, exploit requires local interactive access."
url: https://panop.io/threat-heartbeat/CVE-2026-104660/
---

# CVE-2026-104660 Progressive Robot hMailServer - Broken Access Control

Progressive Robot hMailServer 6.0.0 through 6.3.5 on Windows contains a broken access control vulnerability caused by missing authorization on COM objects, letting local users read/write arbitrary files and send mail as any sender without credentials, exploit requires local interactive access.

CVSS base score 7.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.11% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-104660)

## Details

Type

Broken Access Control

Impact

File System Read, File System Write, Broken Access Control

CVSS vector

CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H

Published

8 October 2026

Updated

15 October 2026

Weakness

[CWE-862](https://cwe.mitre.org/data/definitions/862.html)

## Vendor fix

Update to a version later than 6.3.5 or apply vendor patches addressing COM object authorization.

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

- [https://nvd.nist.gov/vuln/detail/CVE-2026-104660](https://nvd.nist.gov/vuln/detail/CVE-2026-104660)
- [https://gitlab.com/hmailserver/hmailserver/-/work\_items/59](https://gitlab.com/hmailserver/hmailserver/-/work_items/59)
- [https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6](https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.6)

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## What this record can't tell you

- Whether you run the affected software, and where
- Whether an attacker can actually reach and exploit it
- The misconfigurations that never get a CVE number
- What it would cost the business, ranked into what to fix first

Panop answers these inside your environment, for this CVE and every other finding.

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