{"id":"CVE-2026-103010","published":"2026-10-08T11:16:42.117","lastModified":"2026-10-08T21:02:43.860","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.","cvssScore":7.8,"cvssSeverity":"HIGH","cvssVector":"CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H","cwes":["CWE-122"],"vendors":[],"products":[],"references":[{"url":"https://gitlab.com/hmailserver/hmailserver/-/commit/135a1908ff820ed587d5f180f98c53bd010d8931","tags":[]},{"url":"https://gitlab.com/hmailserver/hmailserver/-/releases/v6.3.4","tags":[]},{"url":"https://gitlab.com/hmailserver/hmailserver/-/work_items/49","tags":[]}],"exploitRefs":[],"hasPoc":false,"ai":{"summary":"A heap-based buffer overflow exists in Progressive Robot hMailServer's legacy Blowfish decryption routine that allows a local user to write beyond a 255-byte heap buffer, potentially leading to service crashes or code execution with LocalSystem privileges.","exploitability":"Exploitation is moderately difficult as it requires a local interactive user to pass a long hexadecimal string to the unauthenticated COM method Utilities.BlowfishDecrypt, but the vulnerability is remotely exploitable through local access and could be chained with other local privilege escalation techniques.","blast_radius":"The impact is significant since the hMailServer service runs as LocalSystem by default, meaning successful exploitation could lead to full system compromise with elevated privileges.","remediation":"Upgrade to hMailServer version 6.4.0 or later to address this vulnerability.","detection":"No reliable host or network indicator is derivable from the published description.","tags":["buffer-overflow","local-privilege-escalation","com"],"model":"garnet-coder","analyzedAt":"2026-10-16T09:22:43.047Z"}}