CVE-2021-22659

highpriority · track · 35EPSS 0.018 · 78 %ileEUUS
grimoire priorityP2 · Scheduled
Exploitable?
—
no known exploitation
Likely / severe?
1.80% (78th) EPSS
CVSS 7.5 · high
Is it mine?
4 products
Check your exposure
Who says so?
4 sources
cnnvd · enisa_euvd · cisa_csaf_ot · nvd

EPSS · scored 2026-10-27

Rockwell Automation MicroLogix 1400 Version 21.6 and below may allow a remote unauthenticated attacker to send a specially crafted Modbus packet allowing the attacker to retrieve or modify random values in the register. If successfully exploited, this may lead to a buffer overflow resulting in a denial-of-service condition. The FAULT LED will flash RED and communications may be lost. Recovery from denial-of-service condition requires the fault to be cleared by the user.

01

remediations

Vendor fix, mitigation, or workaround guidance, as published by each source.

No vendor fix yet; a mitigation is available.

  • MitigationMicroLogix 1400 All seriescisa_csaf_ot

    All users, if applicable, may disable Modbus TCP support if it is not necessary for their MicroLogix 1400 implementation. Without Modbus TCP enabled, a potential attacker does not have access to exploit the device using this vulnerability.

02

cvss

Technical severity, 0–10. One row per scoring source.

8.6
010

base score 0–10 · higher = more severe · hover a vector to decode

v2.07.5highAV:N/AC:L/Au:N/C:P/I:P/A:Pprimary · NVD / NIST USexploitability 10 · impact 6.4
v3.18.6highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:Hprimary · NVD / NIST USexploitability 3.9 · impact 4.7
v3.08.1highCVSS:3.0/AV:N/AC:H/PR:N/UI:N/S:C/C:L/I:L/A:Hsecondary · CISA US
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondary · ENISA EU
v3.17.5highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:Hsecondaryexploitability 3.9 · impact 3.6
v3.17.9highCVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:L/I:L/A:H/E:Usecondary · CVSS-BT (t0sche)
03

ssvc

A stakeholder decision — act, attend, or track — from exploitation and impact.

Exploitation: none · Automatable: yes · Technical Impact: partialcoordinatorcisa_ssvcUS
04

weaknesses

The CWE weakness classes this flaw belongs to.

CWE-120USCWE-120US
05

affected products (4)

Products and version ranges known to be affected.

06

advisories (1)

Vendor and ecosystem advisories describing this.

  • ICSA-21-033-01Rockwell Automation MicroLogix 1400 (Update A)2021-02-02icsa · cisa_csaf_otUS

    Successful exploitation of this vulnerability may result in a denial-of-service condition.

07

also known as (3)

Other names and identifiers for this entity.

08

sources

Which sources assert this record, and when.

cnnvdenisa_euvdcisa_csaf_otnvdNVDCVE.orgMITRE
published 2021-03-25modified 2026-06-17
09

references (8)

External citations — patches, advisories, analysis.

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