NVD / CVE Program· CNA GitLab

CVE-2026-100741: Improper Neutralization of Directives in Dynamically Evaluated Code ('Eval Injection') in hMailServer

CriticalCVSS 9.8 · v3.1—No exploit Fix available

Noroxi assessment

Priority: Plan (action score 40/100)

The sources we track (CISA KEV, Exploit-DB, Metasploit, Nuclei, GitHub) show no public exploit code or exploitation in the wild.
Probability of exploitation in the next 30 days: 1.7% (FIRST EPSS); higher than 77.9% of all records.
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.
According to CISA the attack is automatable: targets can be found by mass scanning.
Fixed version: Progressive Robot Ltd hMailServer 6.3.4.

Add it to your regular patch cycle. Upgrade to Progressive Robot Ltd hMailServer 6.3.4 or later.

Generated automatically from the record's data: CVSS (NVD and CNA), CISA KEV and SSVC, FIRST EPSS, exploit sources, fixed versions. How we calculate it

Primary sources: NVD · CVE.org · FIRST EPSS

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.

pre-auth RCE

EUVD-2026-87904

Published: Sep 27, 2026
Updated: Sep 29, 2026
EPSS: 1.7% · 77th percentile
CWE: CWE-95

Report tools

JSON

Action score

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.

Get told when this record changes

Not in KEV: no record of exploitation in the wild
No public exploit code on record
A fix has been released

If any of these changes, we'll tell you in the daily email digest.

Is your version affected? Check it

Noroxi analysis

What does it mean in your environment?

The assessment above is generated automatically from the record's data; it doesn't know your environment. Our team verifies on your systems whether this vulnerability is actually exploitable and which mitigation is enough.

We use this product, ask for help

Affected systems

Is your version affected?

Pick the product and type the version you run. It's compared with this record's version ranges in your browser; the version isn't sent anywhere.

—

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

Same product

progressive robot ltd: all records

Other highest-scoring records for the same primary product.

CVE-2026-126617Improper Neutralization of Special Elements used in an SQL Command ('SQL Injection') in hMailServer
35Monitor
CVE-2026-114489Missing Authorization in hMailServer
32Monitor
CVE-2026-103647Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') in hMailServer
32Monitor

Published before and after this one in the same product

Later →CVE-2026-103010Oct 8, 2026 · Heap-based Buffer Overflow in hMailServer
31Monitor
Later →CVE-2026-103011Oct 8, 2026 · Heap-based Buffer Overflow in hMailServer
26Monitor
Later →CVE-2026-103649Oct 8, 2026 · Synchronous Access of Remote Resource without Timeout in hMailServer
30Monitor

Remediation

Which version to upgrade to

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

Product / package	Fixed version	Source
Progressive Robot Ltd hMailServer	6.3.4	Vendor (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.