CVE-2026-107571
7.8HighPublished 19 Oct 2026 · NVD status: Received · AI triage by gemini-3.8-flash
- Attack vector
- Local
- Complexity
- Low
- Privileges needed
- Low
- User interaction
- None
- Impact
- Full C/I/A compromise
- Weakness
- CWE-276
Impact
A local authenticated user can gain LocalSystem privileges by replacing binaries or planting DLLs in the application directory. This only works if hMailServer was installed outside of Program Files into a directory inheriting permissive parent ACLs, such as the volume root.
Root cause
The Windows installer creates the application and Bin folders without explicit ACLs, causing them to inherit permissive write permissions from parent folders when installed outside Program Files.
Affected systems
Progressive Robot hMailServer 6.0.0 through 6.3.6 (installed in non-default locations with inherited write permissions)
CVSS v3.1 · CVSS:3.1/AV:L/AC:L/PR:L/UI:N/S:U/C:H/I:H/A:H
Fix & remediation
Upgrade to hMailServer 6.3.7 or later. As an immediate workaround, manually remove write and modify permissions for non-administrative users (such as 'Users' or 'Authenticated Users') on the hMailServer installation folder and its Bin directory.
$ icacls "<path_to_hmailserver>" /inheritance:r /grant:r "*S-1-5-32-544":(OI)(CI)F "*S-1-5-18":(OI)(CI)F "*S-1-5-32-545":(OI)(CI)RXAI-suggested. Run it in staging first and check it against the vendor advisory. Why?
NVD description
Incorrect default permissions in the Windows installer of Progressive Robot hMailServer 6.0.0 through 6.3.6 allow a local authenticated user to run code as the mail server's high-privileged accounts when the product is installed in a folder whose permissions are inherited from a writable parent, such as the root of a drive. The installer places the server's programs in the Bin folder of the program folder and gives neither the program folder nor Bin any permissions of their own, so they inherit the parent's. Under the default location, Program Files, ordinary users receive only read and execute and the configuration is not affected; but the installer accepts any path without warning, and a program folder at the root of an NTFS volume inherits write access for a broad group - Authenticated Users (Modify) on a Windows client, Users (create files and folders) on Windows Server. A local user without administrator rights can then alter or replace the service program, which runs as LocalSystem or as the service's virtual account, or the programs an administrator runs elevated from Bin during setup and maintenance, or place a library in Bin that those programs load in place of the system copy, gaining code execution with those privileges. The default Program Files installation is not affected.