Skip to content
Noroxi
CVE-2026-100741· NVD / CVE Program· CNA GitLab

Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') in hMailServer

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.

CriticalCVSS 9.8 · v3.1—No exploit Fix available
Published
Sep 27, 2026
Updated
Sep 29, 2026
EPSS
1.7% · 77th percentile
Follow this CVE

Sign in to follow · You’ll be notified if a followed record enters KEV, gets an exploit or is updated.

Report tools

JSON

Action score

40

Plan

Add it to your regular patch cycle.

CVSS
39 / 40 · 9.8 / 10
CISA KEV
0 / 30 · Not listed
EPSS
1 / 30 · 1.7%

CISA SSVC decision

Exploitation
none
Automatable
yes
Technical impact
total

Vulnrichment: CISA's decision-tree inputs.

CNA vs NVD score

NVD
—
CNA · GitLab
9.8
NVD has not scored this yet; the score shown is the CNA’s.

The score given by the assigning authority versus NVD’s independent score. A gap means the severity is contested.

Affected systems

—

Versions reported by the vendor

Affected version ranges reported by the assigning authority (GitLab). Independent of NVD's CPE analysis and usually ahead of it.

  • Progressive Robot Ltd hMailServer

    • 6.0.0 and later · before 6.3.4affected · semver

Remediation

Which version to upgrade to

Fix versions compiled from the vendor, package registries and Microsoft. Verify the vendor's note before upgrading.

Product / packageFixed versionSource
Progressive Robot Ltd hMailServer6.3.4Vendor (CNA)

Exploit status

No known public exploit

No public exploit has been observed yet. That doesn't mean you're safe, only that the bar is a little higher.

Research context

For pentesters and researchers: attack profile, score disagreement, timeline, patch commits, credits, variant and chain candidates, bug bounty scope. All derived from existing data; no exploit code.

Timeline

From publication to today: proof of concept, Metasploit module, CISA KEV and fix record. Dates are as reported by the sources.

No dated events beyond publication.

EPSS, last 120 days

FIRST EPSS daily score; only changes of 0.01 or more are recorded (step chart).

Patch and commit links

Commit, PR and diff links among the references. A starting point for patch-diffing and variant hunting; fixes, not exploits.

Credits

All researchers

Finders, reporters and analysts named in the CNA record. Click a name for that researcher’s other records.

Variant candidates

Same product, same weakness class, within 18 months. If the patch missed the root cause, the sibling bug is here.

No nightly-computed relations.

Chain candidates

An authentication bypass and a privilege-requiring bug in the same product, published close together: combined they may become an unauthenticated path.

—

Bug bounty scope

No known public program.

Source: bounty-targets-data (public HackerOne, Bugcrowd, Intigriti, YesWeHack listings).

Technical details

Attack conditions

  • Anyone who can reach it over the internet can trigger it.
  • No account or password is required.
  • No user action is required.
  • No special conditions are required; it is repeatable.

If successful

Confidentiality
high · data can be read
Integrity
high · data or configuration can be modified
Availability
high · the service can be disrupted
Attack vector
Network
Attack complexity
Low
Privileges required
None
User interaction
None
Scope
Unchanged
Confidentiality impact
High
Integrity impact
High
Availability impact
High

Weakness class (CWE)

CWE-95 · Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection')

CVSS vector

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

nvd-secondary

Attack context

MITRE CAPEC attack patterns and ATT&CK techniques for this weakness class (CWE). A starting point for detection rules and threat hunting.

Noroxi analysis

No Noroxi analysis for this record yet

We don't hand-write analysis for all 385,000+ vulnerabilities; that wouldn't be honest. For notable, high-impact vulnerabilities our team writes the mechanism, detection and remediation steps.

We use this product, ask for help

Change log

  1. Fix✗ → ✓
  2. SSVC exploitation— → none

For records you follow, these changes also arrive as notifications. →

References

Vendor advisories and official records. Exploit/PoC links are deliberately left out.

All records