dbcve.org
Micrologix 1100 B FirmwareOperating system · Rockwellautomation

CVE-2020-6111

HIGH · 7.5 CVSS v3.1 Published 2020-12-03
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
An exploitable denial-of-service vulnerability exists in the IPv4 functionality of Allen-Bradley MicroLogix 1100 Programmable Logic Controller Systems Series B FRN 16.000, Series B FRN 15.002, Series B FRN 15.000, Series B FRN 14.000, Series B FRN 13.000, Series B FRN 12.000, Series B FRN 11.000 and Series B FRN 10.000. A specially crafted packet can cause a major error, resulting in a denial of service. An attacker can send a malicious packet to trigger this vulnerability.

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

A specially crafted IPv4 packet can cause a major error in Allen-Bradley MicroLogix 1100 PLC Series B devices (versions FRN 10.000-16.000), resulting in denial of service. The vulnerability exists in the IPv4 packet processing functionality, where malformed or malicious packets trigger a fault condition causing the device to become unavailable.

MitigationIsolate affected PLCs behind network firewalls or VLANs to limit exposure to untrusted IPv4 traffic. Apply vendor firmware updates when available, and implement network monitoring to detect DoS conditions. Consider manual fault reset procedures in the incident response plan.

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
Micrologix 1100 B FirmwareOperating system
Affected:= 10.000= 11.000= 12.000= 13.000= 14.000= 15.000= 15.002= 16.000

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 is MicroLogix 1100 Series B
    Locate the physical device label or check device documentation. The device model number and series (B) must be explicitly identified. In RSLogix 500 or Connected Components Workbench, verify the device type in the controller properties.
    Affected if The device is NOT a MicroLogix 1100 Series B model
  2. Check installed firmware version
    In RSLogix 500, go to Controller Properties > Processor Name/Properties to view the firmware revision. Alternatively, access the device web server (if enabled) or use RSLinx Classic to view the device firmware version. Compare against affected versions: 10.000, 11.000, 12.000, 13.000, 14.000, 15.000, 15.002, 16.000.
    Affected if The firmware version falls within the range 10.000 to 16.000 (including 15.002)
  3. Verify IPv4 communication is enabled
    In RSLogix 500, check the channel configuration for Channel 0 (Ethernet). Confirm that Ethernet/IP communication is enabled. Also verify the device has an IP address assigned and is actively communicating on the network.
    Affected if IPv4 Ethernet communication is enabled and the device has an IP address
  4. Assess network exposure to untrusted IPv4 traffic
    Review network architecture to determine if the PLC is directly accessible from untrusted networks. Check firewall rules, VLAN configuration, and whether the device is isolated from external/internet-facing network segments.
    Affected if The device is reachable from untrusted network segments or directly exposed to the internet

You are affected if you have a MicroLogix 1100 Series B running firmware versions 10.000 through 16.000 with IPv4 enabled and network exposure to untrusted traffic.

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

Isolate affected PLCs behind network firewalls or VLANs to limit exposure to untrusted IPv4 traffic. Apply vendor firmware updates when available, and implement network monitoring to detect DoS conditions. Consider manual fault reset procedures in the incident response plan.

Fix this in Micrologix 1100 B Firmware Scoped from the published advisory
  • Consultation6.0 h
  • Implementation8.0 h
  • Testing6.0 h
  • Review / QA4.0 h
24.0 hours of engineering $4,260
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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-2020-6111 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
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