Critical severity · published Sep 1, 2026
CVE-2026-9621
RSLinx Classic® - Multiple Vulnerabilities
9.2
CVSS
0.4%
EPSS
No
On KEV
Description
A denial-of-service security issue exists within RSLinx® Classic. The security issue stems from improper handling of a malformed packet. A crafted CIP packet can cause the RSLinx® Classic service to crash, requiring a restart of the service to recover
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 37% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
RC
RSLinx Classic® · Rockwell Automation
V4.50 and prior · source: vendor
References
NVD
https://nvd.nist.gov/vuln/detail/CVE-2026-9621
CVE.org
https://www.cve.org/CVERecord?id=CVE-2026-9621
www.rockwellautomation.com
https://www.rockwellautomation.com/en-us/trust-center/security-advisories/advisory.SD1794.html
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