---
title: "CVE-2026-103010: Progressive Robot hMailServer - Buffer Overflow"
description: "Progressive Robot hMailServer 6.0.0 through 6.3.3 on Windows contains a heap-based buffer overflow caused by unchecked long hexadecimal input in the BlowFishEncryptor::DecryptFromString routine, letting local users write beyond buffer limits, potentially causing denial of service or code execution, exploit requires local access without authentication."
url: https://panop.io/threat-heartbeat/CVE-2026-103010/
---

# CVE-2026-103010 Progressive Robot hMailServer - Buffer Overflow

Progressive Robot hMailServer 6.0.0 through 6.3.3 on Windows contains a heap-based buffer overflow caused by unchecked long hexadecimal input in the BlowFishEncryptor::DecryptFromString routine, letting local users write beyond buffer limits, potentially causing denial of service or code execution, exploit requires local access without authentication.

CVSS base score 7.8 /10

High

CISA KEV

Not listed

Public exploit

None known

Authentication

Required

EPSS

0.16% chance of exploitation in 30 days

[View the NVD record ↗](https://nvd.nist.gov/vuln/detail/CVE-2026-103010)

## Details

Type

Buffer Overflow

Impact

Denial Of Service, Remote Code Execution

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-122](https://cwe.mitre.org/data/definitions/122.html)

## Vendor fix

Update to a version later than 6.3.3 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

- [https://nvd.nist.gov/vuln/detail/CVE-2026-103010](https://nvd.nist.gov/vuln/detail/CVE-2026-103010)
- [https://gitlab.com/hmailserver/hmailserver/-/work\_items/49](https://gitlab.com/hmailserver/hmailserver/-/work_items/49)
- [https://gitlab.com/hmailserver/hmailserver/-/commit/135a1908ff820ed587d5f180f98c53bd010d8931](https://gitlab.com/hmailserver/hmailserver/-/commit/135a1908ff820ed587d5f180f98c53bd010d8931)
- [https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.4](https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.4)

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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

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