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Simatic Mv540 H FirmwareOperating system · Siemens

CVE-2023-35921

HIGH · 7.5 CVSS v3.1 Published 2023-07-11
Fix available
A fix is available. Upgrade to 3.3.4 or later.
See remediation →
84/100
Remediation priority · High
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
A vulnerability has been identified in SIMATIC MV540 H (All versions < V3.3.4), SIMATIC MV540 S (All versions < V3.3.4), SIMATIC MV550 H (All versions < V3.3.4), SIMATIC MV550 S (All versions < V3.3.4), SIMATIC MV560 U (All versions < V3.3.4), SIMATIC MV560 X (All versions < V3.3.4). Affected devices cannot properly process specially crafted Ethernet frames sent to the devices. This could allow an unauthenticated remote attacker to cause a denial of service condition. The affected devices must be restarted manually.

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

The SIMATIC MV540 and MV550 series devices (H, S, U, X variants) contain a vulnerability in their Ethernet frame processing logic. Specially crafted Ethernet frames sent to affected devices cause a denial of service condition, requiring manual restart to recover. The attack is exploitable remotely without authentication.

MitigationUpgrade all affected devices to firmware version V3.3.4 or later to remediate this vulnerability. Since this is an industrial device, schedule the update during a planned maintenance window and ensure proper backup of device configurations before applying the update.

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
Simatic Mv540 H FirmwareOperating system
Affected:< 3.3.4
Simatic Mv540 S FirmwareOperating system
Affected:< 3.3.4
Simatic Mv550 H FirmwareOperating system
Affected:< 3.3.4
Simatic Mv550 S FirmwareOperating system
Affected:< 3.3.4
Simatic Mv560 U FirmwareOperating system
Affected:< 3.3.4
Simatic Mv560 X FirmwareOperating system
Affected:< 3.3.4

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
None
Integrity
None
Availability
High

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/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. Confirm device model
    Access the device web interface, console, or check network inventory to identify if the device is a Siemens Simatic MV540, MV550, or MV560 series
    Affected if Device model is an MV540, MV550, or MV560 series
  2. Identify device variant
    Check the device label, nameplate, or management interface to determine the variant letter (H, S, U, or X)
    Affected if Device is any variant (H, S, U, or X) of the affected series
  3. Check firmware version
    Query the device through its web interface, SNMP, or console to retrieve the installed firmware version
    Affected if Firmware version is below 3.3.4
  4. Verify Ethernet interface is active
    Check the network configuration in the device management interface to confirm the Ethernet frame processing is enabled
    Affected if Ethernet interface is enabled (required for the vulnerability to be exploitable)

Device is affected if it is a Simatic MV540, MV550, or MV560 variant with firmware version lower than 3.3.4 and has Ethernet connectivity configured.

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 3.3.4 or later
Fixed in 3.3.4
Interim mitigation

Upgrade all affected devices to firmware version V3.3.4 or later to remediate this vulnerability. Since this is an industrial device, schedule the update during a planned maintenance window and ensure proper backup of device configurations before applying the update.

Recommended fix High confidence

Firmware V3.3.4

  1. Obtain the firmware version V3.3.4 or later from Siemens (cert-portal.siemens.com or official Siemens support channels)
  2. Follow Siemens standard firmware upgrade procedure for the specific Simatic MV device model
  3. Upload and install the V3.3.4 firmware onto the affected device
  4. After upgrade, verify the device is operational and running the patched firmware version
  5. Confirm the vulnerability is remediated by testing that crafted Ethernet frames no longer cause denial of service

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

Fix this in Simatic Mv540 H Firmware Scoped from the published advisory
  • Consultation4.0 h
  • Implementation6.0 h
  • Testing3.0 h
  • Review / QA2.0 h
15.0 hours of engineering $2,690
Get the upgrade done

An estimate, not a bill — we confirm scope with you before any work starts. Need it this week? Rush from $4,304.

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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-2023-35921 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