Rockwell products: authentication bypass flaw under attack

What is affected

Rockwell products are found on ordinary personal computers and phones, so this is not only a problem for companies. If you use them and have not updated since the fix was released, you are exposed.

Multiple Rockwell products contain an insufficient protected credentials vulnerability. Studio 5000 Logix Designer software may allow a key to be discovered. This key is used to verify Logix controllers are communicating with Rockwell Automation design software. If successfully exploited, this vulnerability could allow an unauthorized application to connect with Logix controllers. To leverage this vulnerability, an unauthorized user would require network access to the controller.

What an attacker can do

This is a authentication bypass flaw. It lets an attacker get in without a valid username and password and act as a legitimate user, often as an administrator.

How it is reached

Over the internet or network

Access the attacker needs

No account needed

Does the victim have to do something?

No, works without the victim doing anything

What to do

1. Update Rockwell products now. Open the update or "About" screen, install whatever is offered and restart the app or device, because the fix is not active until you do.
2. Turn on automatic updates so the next fix arrives without you having to look for it.
3. If your device is too old to receive this update, stop using the affected app for anything sensitive and plan a replacement.

Apply mitigations per vendor instructions, follow applicable BOD 22-01 guidance for cloud services, or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• support.rockwellautomation.comsupport.rockwellautomation.com/app/answers/answer_view/a_id/1130301/~/cve-2021-22681%3A-au

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on March 5, 2026, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by March 26, 2026, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 64% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 99.2% of all scored vulnerabilities.

Its CVSS severity score is 9.8 out of 10 (critical), as recorded in the US National Vulnerability Database.

Technical description

Rockwell Automation Studio 5000 Logix Designer Versions 21 and later, and RSLogix 5000 Versions 16 through 20 use a key to verify Logix controllers are communicating with Rockwell Automation CompactLogix 1768, 1769, 5370, 5380, 5480: ControlLogix 5550, 5560, 5570, 5580; DriveLogix 5560, 5730, 1794-L34; Compact GuardLogix 5370, 5380; GuardLogix 5570, 5580; SoftLogix 5800. Rockwell Automation Studio 5000 Logix Designer Versions 21 and later and RSLogix 5000: Versions 16 through 20 are vulnerable because an unauthenticated attacker could bypass this verification mechanism and authenticate with Rockwell Automation CompactLogix 1768, 1769, 5370, 5380, 5480: ControlLogix 5550, 5560, 5570, 5580; DriveLogix 5560, 5730, 1794-L34; Compact GuardLogix 5370, 5380; GuardLogix 5570, 5580; SoftLogix 5800.