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Fencer Intel
high 7.5

CVE-2021-33012 json

Rockwell Automation MicroLogix 1100, all versions, allows a remote, unauthenticated attacker sending specially crafted commands to cause th…

published 5y ago modified 4mo ago also EUVD-2021-19733

cvss
7.5
version 3.1, CNA
cisa kev
Not listed
not in CISA's catalog
epss
2.6%
EPSS 2.6% chance of exploitation in 30 days, percentile 85%
public exploits
0
none known

Summary

Rockwell Automation MicroLogix 1100, all versions, allows a remote, unauthenticated attacker sending specially crafted commands to cause the PLC to fault when the controller is switched to RUN mode, which results in a denial-of-service condition. If successfully exploited, this vulnerability will cause the controller to fault whenever the controller is switched to RUN mode.

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Vendor advisories

What the vendors themselves say about their products: affected, fixed or not affected, and what to do.

cisa ICSA-21-189-01 updated cvss 8.6

Rockwell Automation MicroLogix 1100

  • Rockwell Automation MicroLogix 1100
    affected: mitigation “Utilize proper network infrastructure controls, such as firewalls, to help ensure EtherNet/IP traffic from unauthorized sources are blocked.” rockwellautomation.custhelp.com

From CISA ICS and IT advisories (CSAF, https://github.com/cisagov/CSAF), a U.S. Government work; changed: reduced to products, statuses and remediations. CISA notification · csaf

CISA SSVC

Exploitation
none
Automatable
yes
Technical impact
partial
Assessed
5mo ago

Exploit prediction

2.64% chance of exploitation in the next 30 days, higher than 85% of all scored CVEs (FIRST EPSS, 2026-11-09).

CVSS scores

assigned by version score vector
CISA ADP 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 3.1 8.6 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:N/I:N/A:H
CNA 3.1 7.5 CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:N/I:N/A:H
NVD 2.0 5.0 AV:N/AC:L/Au:N/C:N/I:N/A:P

Affected products

  • n/a Rockwell Automation MicroLogix 1100

Classification

Weakness
  • CWE-20 Improper Input Validation

References

Sources

Fencer Intel keeps one entry per vulnerability: the CVE id wins, then GHSA, and records that alias each other are merged, except that two CVEs always keep separate entries. The same data is available as JSON.