CVE 2021-22681 https://www.rockwellautomation.com/en-us/trust-center/security-advisories/advisory.PN1550.html  and send a specially crafted CIP message to the device. If exploited, a threat actor could help prevent access to the legitimate user and end connections to connected devices including the workstation. To recover the controllers, a download is required which ends any process that the controller is running.

A denial-of-service vulnerability exists in the Rockwell Automation affected products when specially crafted packets are sent to the CIP Security Object. If exploited the device will become unavailable and require a factory reset to recover.

An unauthorized user could use a specially crafted sequence of Ethernet/IP messages, combined with heavy traffic loading to cause a denial-of-service condition in Rockwell Automation Logix controllers resulting in a major non-recoverable fault. If the target device becomes unavailable, a user would have to clear the fault and redownload the user project file to bring the device back online and continue normal operation.

A malformed Class 3 common industrial protocol message with a cached connection can cause a denial-of-service condition in Rockwell Automation Logix Controllers, resulting in a major nonrecoverable fault. If the target device becomes unavailable, a user would have to clear the fault and redownload the user project file to bring the device back online.

Rockwell Automation Studio 5000 Logix Designer (all versions) are vulnerable when an attacker who achieves administrator access on a workstation running Studio 5000 Logix Designer could inject controller code undetectable to a user.

An attacker with the ability to modify a user program may change user program code on some ControlLogix, CompactLogix, and GuardLogix Control systems. Studio 5000 Logix Designer writes user-readable program code to a separate location than the executed compiled code, allowing an attacker to change one and not the other.