Rockwell RSLinx Classic DoS Flaws Patched
Rockwell Automation patched four denial-of-service vulnerabilities in RSLinx Classic that let attackers crash the service via crafted CIP packets.
Sourcecisa.gov — open the original
What to check
- Applies to
- The 4 CVEs named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- No exploitation in the wild and no public exploit is recorded for the CVEs named.
CISA published an ICS advisory detailing four denial-of-service vulnerabilities affecting Rockwell Automation's RSLinx Classic software, version 4.50 and earlier, used in critical manufacturing environments worldwide. The flaws (CVE-2026-9621, CVE-2026-9622, CVE-2026-9624, CVE-2026-9625) stem from improper handling of malformed or oversized CIP (Common Industrial Protocol) packets, including issues with integer overflow/underflow, insufficient data length validation, and a classic buffer overflow condition. Successful exploitation causes the RSLinx Classic service to crash, requiring manual restart to restore functionality, but does not appear to enable code execution or data compromise based on the advisory description.
Rockwell Automation has released version 4.60 to address all four vulnerabilities. CISA and Rockwell recommend organizations unable to immediately upgrade apply Rockwell's published security best practices, and reiterate standard ICS hardening guidance: minimizing internet exposure of control system devices, isolating OT networks behind firewalls, and using secure VPN access where remote connectivity is required. No public exploitation of these specific vulnerabilities has been reported to CISA at this time.
This advisory falls into the routine category of ICS vendor disclosures — DoS-only impact, vendor patch available, and no known in-the-wild exploitation — making it a medium-severity concern primarily relevant to Critical Manufacturing sector organizations running affected RSLinx Classic deployments.
Mentioned in this report
Source reporting: https://www.cisa.gov/news-events/ics-advisories/icsa-26-244-01
Free public brief. Slack alerts on the vendors you run come with the paid plans, and a new account gets three days of them, no card.
What this brief leaves out
This page is the free tier: the write-up, the severity, the names. In the app the same report carries live profiles of the CVEs it names. The paid plans add the security research and news reporting the free tier leaves out.
It sits in a corpus of 16,445 reports from 149 sources, 666 of them written in the last seven days, and it grows through the day.
A new account starts with three days of all of it, no card, then keeps the government and CERT reporting free. Slack alerts are a paid-plan feature: name the vendors you run and Slack hears about the reports that touch them, not the rest of the week's. Nothing is charged unless you subscribe.
Create a free account What it costs