Quick answers
- Is CVE-2026-9621 exploited in the wild?
- No. Junglewise Threat Intelligence has no report of CVE-2026-9621 being exploited in the wild.
- How severe is CVE-2026-9621?
- Informational severity, with a CVSS score of 8.6, published 1 September 2026.
- Which products and versions are affected?
- Rockwell Automation RSLinx Classic V4.50 and prior.
- Is there a fix for CVE-2026-9621?
- No fixed version is recorded yet. Check the vendor's advisory in the references below. If you run it, Junglewise drafts a mitigation that fits your setup and applies it once you approve, with senior security engineers behind it.
- How is CVE-2026-9621 attacked?
- It is attacked over the network.
- Am I affected by CVE-2026-9621?
- Check whether you run Rockwell Automation RSLinx Classic at an affected version. Junglewise does that check for you around the clock: connect your code, cloud and domains, and it matches new vulnerabilities like this one against what you actually run and tells you when one reaches you.
Technical details
CVE-2026-9621 is a denial-of-service vulnerability caused by improper handling of malformed CIP (Common Industrial Protocol) packets in RSLinx Classic. The root cause is an integer overflow (CWE-190) in packet parsing logic. An unauthenticated remote attacker can send a specially crafted CIP packet to the service to trigger a crash. No workarounds are available; affected versions V4.50 and prior must be upgraded to V4.60 or later to remediate.
Affected products
- Rockwell Automation RSLinx Classic V4.50 and prior
Timeline
- 2026-09-01: disclosed