Description
Heap-based buffer overflow in the legacy Blowfish decryption routine (BlowFishEncryptor::DecryptFromString) in Progressive Robot hMailServer 6.0.0 through 6.3.3 on Windows allows a local interactive user with no hMailServer credentials to write bytes of their choosing past the end of a 255-byte heap buffer in the hMailServer service process, which runs as LocalSystem by default. The user does this by passing a long hexadecimal string to the COM method Utilities.BlowfishDecrypt, which checked no authentication. The routine converted hexadecimal input of any length into a fixed 255-byte buffer before decrypting it in place. The result is a denial of service (service crash), and possibly code execution with the privileges of the service account.
Published: 2026-10-08
Score: 7.8 High
EPSS: n/a
KEV: No
Impact: n/a
Action: n/a
AI Analysis

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Remediation

Vendor Solution

Upgrade to hMailServer 6.3.6, which also requires authentication for the COM Utilities helpers (6.3.4 is the first release with this routine fixed).

Tracking

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Advisories

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History

Thu, 08 Oct 2026 11:00:00 +0000

Type Values Removed Values Added
Description Heap-based buffer overflow in the legacy Blowfish decryption routine (BlowFishEncryptor::DecryptFromString) in Progressive Robot hMailServer 6.0.0 through 6.3.3 on Windows allows a local interactive user with no hMailServer credentials to write bytes of their choosing past the end of a 255-byte heap buffer in the hMailServer service process, which runs as LocalSystem by default. The user does this by passing a long hexadecimal string to the COM method Utilities.BlowfishDecrypt, which checked no authentication. The routine converted hexadecimal input of any length into a fixed 255-byte buffer before decrypting it in place. The result is a denial of service (service crash), and possibly code execution with the privileges of the service account.
Title Heap-based Buffer Overflow in hMailServer
Weaknesses CWE-122
References
Metrics cvssV3_1

{'score': 7.8, 'vector': 'CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H'}


Subscriptions

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cve-icon MITRE

Status: PUBLISHED

Assigner: GitLab

Published:

Updated: 2026-10-08T10:53:10.627Z

Reserved: 2026-09-29T21:04:45.349Z

Link: CVE-2026-103010

cve-icon Vulnrichment

No data.

cve-icon NVD

Status : Received

Published: 2026-10-08T11:16:42.117

Modified: 2026-10-08T11:16:42.117

Link: CVE-2026-103010

cve-icon Redhat

No data.

cve-icon OpenCVE Enrichment

Updated: 2026-10-08T12:30:04Z

Weaknesses
  • CWE-122

    Heap-based Buffer Overflow