CVE-2026-100741

9.8 CRITICAL

Published 2026-09-27 · Updated 2026-09-29

AI risk analysis

Summary: The flaw allows a remote, unauthenticated attacker to inject JScript code into hMailServer, potentially leading to command execution as the service account.
Exploitability: Exploitation requires specific configurations (event scripting enabled, JScript set as the script language, and defined handlers) and is moderately hard due to these preconditions.
Blast radius: If exploited, the attacker could gain full control over the hMailServer service, impacting email delivery and server integrity.
Detection: No reliable host or network indicator is derivable from the published description.
Prioritized remediation: Disable event scripting or ensure it is not enabled by default, and update to hMailServer version 6.2.25 or later.

rceauth-bypasswindowsemail

Analysis generated locally by qwen2.5:7b-instruct (no data left the box). AI-assisted — verify against primary sources before acting.

NVD description

Eval injection in the JScript event-script dispatcher in Progressive Robot Ltd's hMailServer, versions 6.0.0 through 6.3.3 on Windows, allows a remote, unauthenticated attacker to run arbitrary JScript inside the hMailServer service process, with the privileges of the service account, via a password containing a backslash followed by an apostrophe, sent in any logon (SMTP AUTH, POP3, IMAP) that names an existing, active account. Exploitation requires a non-default configuration: event scripting enabled (off by default), the script language set to JScript (the default is VBScript), and an OnClientValidatePassword handler defined in the event script. The server wrote event values into the handler call as JScript string literals, escaping the apostrophe but not the backslash, so such a value closes the literal and the rest of it is parsed as script. The same flaw is reachable by a remote POP3 server through the message UID it returns, where an OnExternalAccountDownload handler is defined, and by a remote SMTP server through the error reply it rejects a delivery with, where an OnDeliveryFailed handler is defined. Before 6.2.25 the injected script can create any COM object, and from 6.2.25 it can with the default ScriptAllowedObjects value of '*'; WScript.Shell among them gives command execution as the service account. VBScript event scripts and the Linux builds of Progressive Robot Ltd's hMailServer are not affected.

CVSS vector

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Weaknesses

CWE-95

All references

Source data: NVD (nvd.nist.gov), public domain. Exploit-DB.ai adds local AI analysis for defensive use only.

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