Vulnerability details

CVE-2026-103010

Progressive Robot hMailServer

Heap-based Buffer Overflow in hMailServer

CVSS 3.1

7.8High

Official 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.

CVSS scores

Score	Version	Source	Vector
7.8High	3.1	CVEProject cvelistV5 (CNA) (GitLab)	`CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H`

Affected products

Vendor	Product	Versions	Source
Progressive Robot Ltd	hMailServer	6.0.0 ≤ v < 6.3.4	CVEProject cvelistV5 (CNA)

References and advisories

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Details

Published: 2026-10-08
Last updated: 2026-10-08
State: Published
Assigner (CNA): GitLab

Exploit prediction (EPSS)

0.16%

Probability of exploitation in 30 days

5.4%

Percentile (among all CVEs)

SSVC assessment (CISA)

Automatable: No
Exploitation: None
Technical impact: Total

Weaknesses (CWE)

CWE-122
Heap-based Buffer Overflow