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Pm554 FirmwareOperating system · Abb

CVE-2020-24686

HIGH · 7.5 CVSS v3.1 Published 2021-02-26
Mitigation only
No fix yet — a mitigation exists. There is no fixed release. A documented workaround reduces exposure in the meantime.
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
The vulnerabilities can be exploited to cause the web visualization component of the PLC to stop and not respond, leading to genuine users losing remote visibility of the PLC state. If a user attempts to login to the PLC while this vulnerability is exploited, the PLC will show an error state and refuse connections to Automation Builder. The execution of the PLC application is not affected by this vulnerability. This issue affects ABB AC500 V2 products with onboard Ethernet.

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 · moderate confidence

This is a denial-of-service vulnerability affecting the web visualization component of ABB AC500 V2 PLCs with onboard Ethernet. An unauthenticated attacker can exploit this to cause the web visualization to stop responding, resulting in loss of remote visibility for legitimate users. When users attempt to login during exploitation, the PLC enters an error state and refuses connections to Automation Builder, though the core PLC application execution remains unaffected.

MitigationNetwork segmentation and firewall rules should be implemented to restrict unauthorized access to the PLC's web interface. Apply vendor firmware updates when available and monitor for unusual traffic patterns targeting the web visualization service.

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
Pm554 FirmwareOperating system
Affected:all versions
Pm556 FirmwareOperating system
Affected:all versions
Pm564 FirmwareOperating system
Affected:all versions
Pm566 FirmwareOperating system
Affected:all versions
Pm572 FirmwareOperating system
Affected:all versions
Pm573 FirmwareOperating system
Affected:all versions

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. Identify PLC model and firmware version
    Check the device label on the physical PLC unit, or query the PLC via Automation Builder or its management interface to confirm the model number (PM554, PM556, PM564, PM566, PM572, or PM573) and current firmware version
    Affected if The device is any of these six models (PM554, PM556, PM564, PM566, PM572, PM573) regardless of firmware version, as all versions are affected
  2. Confirm web visualization is enabled
    Access the PLC configuration via Automation Builder and verify whether the web visualization component (web server feature) has been enabled in the project settings or PLC configuration
    Affected if Web visualization is enabled and the PLC's onboard Ethernet web interface is accessible on the network
  3. Test web interface accessibility
    Attempt to reach the PLC's web interface via HTTP/HTTPS from an authorized network segment using the PLC's IP address. Document whether the page loads, times out, or returns an error
    Affected if The web interface fails to respond, returns connection errors, or shows an error state when legitimate users attempt to access it
  4. Check for PLC error state via Automation Builder
    Connect to the PLC using Automation Builder and observe the device status. Look for error indicators or connection refusal messages when attempting to establish a session
    Affected if Automation Builder reports the PLC is in an error state or refuses connection attempts, especially when the web interface is also unresponsive

If you have an ABB AC500 V2 PLC model PM554, PM556, PM564, PM566, PM572, or PM573 with web visualization enabled and the web interface is unresponsive or the PLC shows an error state to Automation Builder, your environment is likely affected by this CVE.

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.

From vendor data
Mitigation available No clean upgrade yet — mitigate in the meantime
Mitigation

Network segmentation and firewall rules should be implemented to restrict unauthorized access to the PLC's web interface. Apply vendor firmware updates when available and monitor for unusual traffic patterns targeting the web visualization service.

Fix this in Pm554 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-2020-24686 in production — separate from our analysis above.

No notes yet

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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
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  • Version or environment caveats, and links to real fixes
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