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VulnerabilityPublished Updated

CVE-2026-100741: Progressive Robot hMailServer · Eval Injection

Affects Progressive Robot hMailServerSource CVE Database V5

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Not known to be exploited · CVSS 9.8 Critical : upgrade to 6.3.4 as a priority.

Data as of 10 Nov 2026, 23:24 UTC

CVSS 3.1 base score
9.8Critical
How severe the flaw is on the 0–10 CVSS scale.
EPSS
1.7% chance of exploitation in 30 days – higher than 77% of CVEsExploit Prediction Scoring System: the likelihood attackers will use this flaw soon.
Patch
Available – fixed in 6.3.4
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Exploitation evidence

  1. Disclosed: evidence found.

    CVE published 27 Sep 2026

  2. Detectable: no evidence on record.

    No public nuclei template indexed

  3. Weaponized: no evidence on record.

    No public exploit code indexed in Metasploit or Exploit-DB

  4. Exploited in the wild: no evidence on record.

    Not in CISA KEV and no source reports exploitation

  5. Observed by OffSeq Mirage: no evidence on record.

    No attack traffic recorded by OffSeq Mirage sensors

A missing step is not evidence of safety. Sources: cve.org (opens in a new tab), the Metasploit, Exploit-DB and nuclei-templates index as of 10 Nov 2026.

What to do

Upgrade hMailServer and progressiverobot/hmailserver to 6.3.4.

Affected software

ProductAffectedFixed in
Progressive Robot LtdhMailServerAffected
  • >=6.0.0 <6.3.4
Fixed in
  • 6.3.4
GitHubprogressiverobot/hmailserverpkg:github/progressiverobot/hmailserverOther threatsAffected
  • >=6.0.0 <6.3.4
Fixed in
  • 6.3.4

Check your own hosts for these packages with threat-finder (opens in a new tab), our free open-source scanner.

AI-suggested

A fix is available in hMailServer version 6.3.4 and later. Users should upgrade to version 6.3.4 or newer to remediate this vulnerability. If upgrading is not immediately possible, disabling event scripting or avoiding the use of JScript as the event script language and removing the vulnerable event handlers can mitigate the risk. Review and adjust the ScriptAllowedObjects setting to restrict COM object creation if applicable.

Description

CVE-2026-100741 is a critical eval injection vulnerability in Progressive Robot Ltd's hMailServer versions 6.0.0 through 6.3.3 on Windows. It allows a remote unauthenticated attacker to execute arbitrary JScript code with service account privileges via crafted passwords or certain message fields when event scripting is enabled with JScript and specific event handlers are defined. The vulnerability does not affect VBScript event scripts or Linux builds. Exploitation requires non-default configurations enabling JScript event scripting and relevant handlers.

References

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