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No exploitation reportedAwaiting NVD analysis

CVE-2026-100741

No exploitation reported by the sources we read.

  • Published2026-09-27
  • WeaknessCWE-95

Am I affected?

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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.

Timeline

dates in UTC
  1. 2026-09-2708:16CVE publishedNVD

Versions per branch

Products declared by the CNA

As GitLab, the CNA that assigned this CVE, declared them in the CVE record; versions as written. NVD lists no product for this CVE yet: this is the only product data so far.

  • Progressive Robot Ltd hMailServerother versions: not affected
    Affected
    • ≥ 6.0.0, < 6.3.4fixed in 6.3.4semver

Source: the CNA record (CVE Program), © The MITRE Corporation,CVE Terms of UseCVE recordupdated 2026-09-27

Neither OSV.dev nor the vendor advisories we read list affected versions for CVE-2026-100741 yet.

Full record on NVD

Fix

No fix published by the sources we read yet. NVD record

Detection

Nuclei template
none so far
ProjectDiscovery
Exploit-DB
no entry
Exploit-DB
Proof of concept
Metasploit modules
none listed
Metasploit Framework

Sources

Identifiers

Technical details

CVSS v3 Vector
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Published
2026-09-27
Last Modified
2026-09-29
NVD status
Awaiting Analysis
GitHub Advisory
GHSA-v6j4-p35g-mq6p

Frequently asked questions

What is CVE-2026-100741?

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.

Is CVE-2026-100741 actively exploited?

Active exploitation of CVE-2026-100741 has not been confirmed. Its EPSS score was 1.7% on 2026-11-10, the estimated probability of exploitation in the next 30 days.

What is the CVSS score for CVE-2026-100741?

CVE-2026-100741 has a CVSS v3 base score of 9.8 (CRITICAL severity), with vector string CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H.

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