CVE-2026-114471

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SMTP Server Logs Exposure in hMailServer

Publication date: 2026-10-21

Last updated on: 2026-10-29

Assigner: GitLab Inc.

Description

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.

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Meta Information

Published

2026-10-21

Last Modified

2026-10-29

Generated

2026-11-10

AI Q&A

2026-10-21

EPSS Evaluated

2026-11-09

NVD

CVE-2026-114471

EUVD

EUVD-2026-107314

Affected Vendors & Products

Vendor	Product	Version / Range
Progressive Robot Ltd	hMailServer	6.0.0

Helpful Resources

Exploitability

CWE

KEV

CWE ID	Description
CWE-532	The product writes sensitive information to a log file.

Attack-Flow Graph

Executive Summary

This vulnerability involves hMailServer's SMTP server logging sensitive authentication credentials in plaintext under specific conditions when SMTP logging is enabled. It affects versions 6.0.0 through 6.3.6 and occurs when credentials like OAuth 2.0 tokens, SCRAM-SHA-256 proofs, or PLAIN passwords are sent before EHLO or in unusual formats. These credentials are then stored in log files, which can be accessed by unauthorized users.

Detection Guidance

Check SMTP log files for plaintext credentials. Look for lines containing AUTH PLAIN, AUTH XOAUTH2, AUTH OAUTHBEARER, or SCRAM-SHA-256 in logs under the hMailServer log directory. On Windows, verify log file permissions allow only authorized users to read them.

Impact Analysis

If exploited, this vulnerability allows attackers with access to log files to obtain credentials, impersonate accounts, perform offline password guessing, or gain unauthorized access. On Windows systems before version 6.3.6, local users could read logs due to weak file permissions, increasing exposure risk.

Compliance Impact

This vulnerability likely violates compliance requirements such as GDPR and HIPAA, which mandate protection of sensitive data like authentication credentials. Logging such data exposes organizations to legal and regulatory penalties due to unauthorized access risks.

Mitigation Strategies

Disable SMTP logging in hMailServer settings. Restrict log file access to authorized users only. Upgrade to version 6.3.7 or later to mask sensitive data in logs. Purge old logs containing credentials and change exposed passwords or revoke tokens.

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