CVE-2020-24685Network attack vector

PLC shutdown via unauthenticated crafted packet

Published Feb 9, 2021 · Updated Aug 4, 2024

Denial of service in ABB AC500 V2 firmware 2.8.4 and earlier allows remote attackers to stop the PLC with a crafted packet. The onboard Ethernet interface accepts a single unauthenticated network packet that puts the controller into an error state; ABB has not disclosed the malformed field or processing flaw. No user interaction or credentials are required, and restoring the PLC application after the stop requires physical access.

CVSS severity8.6
High
EPSS probability1.61%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

Denial of service in ABB AC500 V2 firmware 2.8.4 and earlier allows remote attackers to stop the PLC with a crafted packet. The onboard Ethernet interface accepts a single unauthenticated network packet that puts the controller into an error state; ABB has not disclosed the malformed field or processing flaw. No user interaction or credentials are required, and restoring the PLC application after the stop requires physical access.

The record

CVE
CVE-2020-24685
Published
Feb 9, 2021
Updated
Aug 4, 2024
Vendor
ABB
Product
AC500
Classifications
CWE-789, CWE-770, T0814
Attack vector
network
Privileges
unauthenticated

Timeline

How it unfolded

  1. Feb 9, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

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Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=version 2.8.4 and prior versions

What conditions does exploitation require?

Attack vectornetwork
Required privilegesunauthenticated

What is affected?

ABB · AC500version=version 2.8.4 and prior versions

Published CVSS scores

5.0NVDAV:N/AC:L/Au:N/C:N/I:N/A:P
8.6ABBCVSS:3.0/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
8.6NVDCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesunauthenticated
Known exploitationUnconfirmed
Public exploitUnconfirmed

Weakness, pattern, technique

CWE-789Memory Allocation with Excessive Size Value
CWE-770Allocation of Resources Without Limits or Throttling
T0814Denial of Service

Public exploit references

No public exploit references are available in this record.

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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