CVE-2026-126622
Incorrect Default Permissions in hMailServer
Incorrect default permissions in the Windows installer of Progressive Robot hMailServer 6.3.7 allow a local authenticated user to run code as the administrator who runs setup, when the server is installed into a program folder that is already there and that accounts other than the administrators could write, such as a folder made beforehand at the root of a drive, or when such an installation is upgraded or repaired. 6.3.7 fixed CVE-2026-107571 by giving the program folder, Bin and ControlPanel permissions that only administrators may change, but for a folder that is already there it does so only at the end of setup: setup first copies the programs into Bin, which every user may still write, and runs programs from Bin with the administrator's elevated rights, registering the service among them, before that hardening, so that a library another account places in Bin meanwhile is loaded in place of the system's. A handle an account opened on such a folder while it could write it keeps that access after the hardening. The default installation under Program Files, whose folders give ordinary users read and execute only, is not affected.
Fixes and workarounds
Fix
Upgrade to hMailServer 6.3.8, whose setup hardens a program folder, Bin and ControlPanel that are already there before it stops the service, copies a file or runs a program of the installation, reading each through a handle it holds; refuses to install into one it cannot harden, or one another account owns that is not the earlier installation's; makes an empty Bin or ControlPanel again rather than use it; and, where another account could change one of the program's folders before this installation, hardens it and refuses to install until Windows has restarted, which closes any handle opened while it could. Until then, install hMailServer under Program Files, or into a new folder inside one that only administrators may change. Before running setup into or over a program folder in a location other accounts can write, follow from an elevated Command Prompt the steps in the hMailServer documentation, ServiceAccount.md, "Before upgrading an installation at a drive's root", which make the program folder, Bin and ControlPanel the Administrators' with a protected set of permissions, then restart Windows before running setup. Where accounts that are not administrators could change the folder before, reinstall into a new folder as that page's "Reinstalling into a new folder" says.
Source: CNA: GitLabAffected products and versions
| Product | Versions | Authority |
|---|---|---|
| hMailServer Progressive Robot Ltd |
6.3.7 (affected)
Other versions: unaffected |
CNA: GitLab |
Version ranges are source assertions. Check the vendor advisory and your installed configuration before determining exposure.
CVSS assessments
| Version / score | Vector | Authority |
|---|---|---|
| 3.1 / 7.3 high |
CVSS:3.1/AV:L/AC:L/PR:L/UI:R/S:U/C:H/I:H/A:H | CNA: GitLab |
Exploit evidence
No exploit evidence in collected sources. This is not proof of no exploitation.
References
For agents and automation
Read public disclosures for free as Markdown or JSON. Compatible browsers also expose native WebMCP tools to search disclosures, read this page, and discover API access.
Use the ontology-linked Cyber API with x402 pay per request, or a Y2 Pro or Elite API key with the intel:cyber scope.
Endpoints and access details
https://api.y2.dev/api/v2/cyber/cveshttps://api.y2.dev/api/v2/cyber/cves/{cveId}
A workspace owner or admin can create a Pro or Elite API key. Send Authorization: Bearer <Y2_API_KEY> from your trusted agent runtime.
For x402, omit Authorization and read the HTTP 402 payment challenge before signing a retry. Public browser tools do not make payments.