---
id: "CVE-2026-114471"
kind: "vulnerability"
aliases: ["CVE-2026-114471"]
title: "hMailServer: SMTP log leaks login credentials and tokens in plain text"
severity: "medium"
cvss: 4.7
epss: 0.00097
exploited: false
status: "open"
category: "package"
products: []
ecosystems: []
tags: ["email", "hmailserver", "package", "self-hosted", "windows"]
not_affected_if: ["default-config", "logging-disabled"]
published_at: "2026-10-21T16:17:34+00:00"
first_seen_at: "2026-10-23T21:57:29+00:00"
updated_at: "2026-10-25T04:34:54+00:00"
sources: [{"source": "nvd", "url": "https://nvd.nist.gov/vuln/detail/CVE-2026-114471", "first_seen_at": "2026-10-23T21:57:29+00:00"}, {"source": "epss", "url": "https://api.first.org/data/v1/epss?cve=CVE-2026-114471", "first_seen_at": "2026-10-24T13:15:54+00:00"}]
---

# hMailServer: SMTP log leaks login credentials and tokens in plain text

hMailServer writes parts of SMTP AUTH exchanges into its SMTP log, including PLAIN passwords sent in some forms, OAuth bearer tokens, SCRAM client proofs and GSSAPI data. Anyone who can read that log, or gets a copy of it, can take those credentials or guess the password offline.

_Summary, check and fix written by a model from the sources; labelled as such._

## How to check

- Check whether SMTP logging is enabled in the hMailServer Administrator under Settings, Advanced, Logging (it is off by default).
- On Windows, check the log folder permissions and confirm only administrators and the service account can read it.
- Check the installed version (`hMailServer` version in the Administrator) against the affected range `6.0.0` through `6.3.6`.

## Fix

- Upgrade hMailServer to `6.3.6` or later, which fixes the log folder permissions on Windows.
- Turn off SMTP logging if it is not needed.
- Rotate passwords and OAuth tokens for mail accounts whose SMTP logs were readable by other users or copied elsewhere.

## Timeline

- 2026-10-23T21:57:29+00:00 nvd https://nvd.nist.gov/vuln/detail/CVE-2026-114471
- 2026-10-24T13:15:54+00:00 epss https://api.first.org/data/v1/epss?cve=CVE-2026-114471

## From the sources

Insertion of sensitive information into a log file in the SMTP server of Progressive Robot hMailServer 6.0.0 through 6.3.6 allows a local user who can read the server's log, or anyone given a copy of it, to obtain credentials. With SMTP logging enabled, the server hid the credential of an AUTH PLAIN command only when it was sent after EHLO in one exact form, and wrote the rest of the SASL exchange as the client sent it: a PLAIN password sent before EHLO or with extra spacing, the OAuth 2.0 bearer token of AUTH XOAUTH2 and AUTH OAUTHBEARER (from 6.2.0), the SCRAM-SHA-256 client proof (from 6.2.0), which with the logged salt and iteration count allows offline password guessing, and the GSSAPI authenticator (from 6.3.2). SMTP logging is off by default; on Windows before 6.3.6 the log folder was readable by every local user.

---

_Free to read at a human pace. An API with keys and an MCP server are in preparation; early access: hello@infrastack.ai_