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Mx Se FirmwareOperating system · Zultys

CVE-2023-43742

CRITICAL · 9.8 CVSS v3.1 Published 2023-12-08
Fix available
A fix is available. Upgrade to 16.0.4 / 17.0.10 or later.
See remediation →
100/100
Remediation priority · Urgent
Remotely reachable No privileges Zero-click

Official description Straight from the sourceThe vendor's or NVD's own wording, published unedited. Authoritative, but often terse — it says what broke, rarely what to do.

NVD · unedited
An authentication bypass in Zultys MX-SE, MX-SE II, MX-E, MX-Virtual, MX250, and MX30 with firmware versions prior to 17.0.10 patch 17161 and 16.04 patch 16109 allows an unauthenticated attacker to obtain an administrative session via a protection mechanism failure in the authentication function. In normal operation, the Zultys MX Administrator Windows client connects to port 7505 and attempts authentication, submitting the administrator username and password to the server. Upon authentication failure, the server sends a login failure message prompting the client to disconnect. However, if the client ignores the failure message instead and attempts to continue, the server does not forcibly close the connection and processes all subsequent requests from the client as if authentication had been successful.

Technical summary Written by usOur analysis, written from the advisory, the CVSS vector and the affected-version data. It adds context the advisory leaves out, and never invents facts that are not in the source.

dbcve analysis · high confidence

Zultys MX voice appliance authentication bypass where the server accepts client connections even after failed authentication if the client ignores the login failure response. An unauthenticated attacker can connect to port 7505, ignore the authentication failure message, and send administrative commands that are processed with full administrative privileges.

MitigationUpgrade Zultys MX firmware to version 17.0.10 patch 17161 or 16.04 patch 16109 or later to remediate the authentication bypass.

Verify against the referenced sources before acting — the references below are authoritative for this CVE, this summary is not.

Affected products & versions What the vendor confirmedThe version ranges the vendor confirmed as vulnerable. If your version sits inside a range here, treat yourself as exposed until you have upgraded.

NVD · CPE data
Mx Se FirmwareOperating system
Affected:< 16.0.4>= 17.0.6, < 17.0.10
Mx Se Ii FirmwareOperating system
Affected:< 16.0.4>= 17.0.6, < 17.0.10
Mx E FirmwareOperating system
Affected:< 16.0.4>= 17.0.6, < 17.0.10
Mx Virtual FirmwareOperating system
Affected:< 16.0.4>= 17.0.6, < 17.0.10
Mx250 FirmwareOperating system
Affected:< 16.0.4>= 17.0.6, < 17.0.10
Mx30 FirmwareOperating system
Affected:< 16.0.4>= 17.0.6, < 17.0.10

CVSS breakdown How the score is builtThe industry scoring standard. It rates how the flaw is reached, what it takes to exploit, and what an attacker gains — the score is derived from those, not the other way round.

From the vector
Attack vector
Network
Complexity
Low
Privileges
None
User interaction
None
Scope
Unchanged
Confidentiality
High
Integrity
High
Availability
High

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

Am I affected? How to checkSteps we derive from the advisory and the affected-version data, so you can decide whether this CVE reaches your setup. They are a guide, not a scan — your own configuration is the authority.

dbcve checks

Work through these to decide whether this CVE applies to you.

  1. Identify the Zultys MX product model
    Log into the device administrative interface or check the device label to determine the exact model (MX Se, MX Se II, MX E, MX Virtual, MX250, or MX30)
    Affected if The model is any of the affected Zultys MX product lines
  2. Determine the installed firmware version
    Access the device administrative interface and navigate to the system status or firmware information page to view the current firmware version
    Affected if The firmware version is less than 16.0.4, OR is greater than or equal to 17.0.6 but less than 17.0.10
  3. Check if port 7505 is exposed
    From an external system, use a network scanner or the command 'nc -zv <device_ip> 7505' or 'telnet <device_ip> 7505' to test connectivity to port 7505
    Affected if Port 7505 is accessible from an untrusted network or the internet

The environment is affected if the Zultys MX device runs firmware version less than 16.0.4, or version 17.0.6 through 17.0.9, and port 7505 is exposed to an untrusted network.

Generated from the published advisory. Verify against your own configuration.

Check your environment

Paste your version and any relevant configuration and it will be compared against the affected criteria above. Do not include secrets or credentials.

AI-assisted, checked against the advisory. Informational, not a guarantee.

Remediation Closing itWhat it takes to close this. Where a vendor fix exists we point at it; where none exists we say so plainly, and can build one. Effort estimates are scoped from the advisory, not from your codebase.

dbcve · scoped
Upgrade available Upgrade to 16.0.4 / 17.0.10 or later
Fixed in 16.0.417.0.10
Interim mitigation

Upgrade Zultys MX firmware to version 17.0.10 patch 17161 or 16.04 patch 16109 or later to remediate the authentication bypass.

Recommended fix High confidence

Zultys MX 16.0.4 (patch 16109) or 17.0.10 (patch 17161) depending on current branch

  1. Identify the current firmware version of the Zultys MX device using the administrative interface or CLI
  2. Determine which firmware branch is currently running (16.x or 17.x)
  3. For devices running 16.x firmware: Upgrade to firmware version 16.0.4 with patch 16109 or later
  4. For devices running 17.x firmware: Upgrade to firmware version 17.0.10 with patch 17161 or later
  5. After upgrade, verify the firmware version and patch level in the administrative interface
  6. Confirm that the authentication mechanism now properly terminates connections on failed authentication attempts
  7. Test the administrative login to ensure normal authentication functions correctly
Caveat Review Zultys release notes for any configuration or feature changes between current version and target upgrade version

Generated from the published advisory — verify against the referenced sources before acting.

Fix this in Mx Se Firmware Scoped from the published advisory
  • Consultation2.0 h
  • Implementation3.0 h
  • Testing2.0 h
  • Review / QA1.0 h
8.0 hours of engineering $1,420
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References Go to the primary sourcePrimary sources — vendor advisories, patches and trackers. Where our summary and a reference disagree, the reference wins.

Primary sources

Practitioner notes

Contributed

Peer-ranked notes from engineers who’ve handled CVE-2023-43742 in production — separate from our analysis above.

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What this is

A place for practitioners to share what actually worked: a mitigation you’ve tested, a configuration change, a version- or environment-specific caveat, or a link to a verified patch. The most useful notes rise to the top as peers upvote them, so the signal stays high.

What belongs here
  • Verified mitigations, workarounds, and config changes
  • Version or environment caveats, and links to real fixes
  • No weaponised exploit code, or anything meant to cause harm
  • No spam, self-promotion, credentials, or personal data