Rockwell Automation RSLinx Classic

September 1, 2026·Source: CISA

0 comments

TL;DR

View CSAF Summary Successful exploitation of these vulnerabilities could allow an attacker to cause a denial-of-service condition on the affected product. The following versions of Rockwell Automation RSLinx Classic are affected: RSLinx Classic <=4.50 (CVE-2026-9621, CVE-2026-9622, CVE-2026-9624, CVE-2026-9625) CVSS Vendor Equipment Vulnerabilities

v3 8.6 Rockwell Automation Rockwell Automation RSLinx Classic Integer Overflow or Wraparound, Integer Underflow (Wrap or Wraparound), Buffer Copy without Checking Size of Input ('Classic Buffer Overflow')

Background Critical Infrastructure Sectors: Critical Manufacturing Countries/Areas Deployed: Worldwide Company Headquarters Location: United States Vulnerabilities Expand All + CVE-2026-9621 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. View CVE Details Affected Products Rockwell Automation RSLinx Classic Vendor: Rockwell Automation Product Version: Rockwell Automation RSLinx Classic: <=4.50 Product Status: known_affected Remediations Vendor fix Rockwell Automation has corrected the vulnerabilities in RSLinx Classic version 4.60. Mitigation Users using the affected software, who are not able to upgrade to one of the corrected versions, should use Rockwell Automation's security best practices https://support.rockwellautomation.com/app/answers/answer_view/a_id/1085012/loc/en_US#__highlight. https://support.rockwellautomation.com/app/answers/answer_view/a_id/1085012/loc/en_US#__highlight Mitigation For more information, see Rockwell Automation Security Advisories: https://www.rockwellautomation.com/en-us/trust-center/security-advisories.html. https://www.rockwellautomation.com/en-us/trust-center/security-advisories.html Relevant CWE: CWE-190 Integer Overflow or Wraparound Metrics CVSS Version Base Score Base Severi

What Happened

Rockwell Automation RSLinx Classic, reported by CISA.

For the full technical details, see the original report.

Why It Matters for Businesses

This development could affect organizations that rely on the impacted technologies or services. Unpatched systems, misconfigured infrastructure, or lack of monitoring can leave businesses exposed to exploitation, data breaches, and regulatory penalties.

How to Check Your Exposure

Run a free scan on NEL Professional's Cyber Risk Scanner to check whether your domain is affected. The scan covers SSL/TLS, security headers, DNS configuration, email authentication, and more across 16 modules.

Check Your Domain Security

Mitigation Steps

Patch immediately, Apply vendor patches or updates as soon as they are available.
Review configurations, Check firewall rules, access controls, and security headers.
Monitor logs, Watch for indicators of compromise (IOCs) related to this threat.
Update security policies, Ensure incident response plans cover this type of threat.
Run a security scan, Use automated tools to verify your exposure.

Need Expert Help?

If your organization needs help assessing or remediating this issue, hire a verified cybersecurity specialist through NEL Professionals.

Need More Scan Credits?

Get up to 100 scans or unlimited lifetime access starting at $15.

View Plans →

Comments (0)

No comments yet. Be the first to comment!

← Back to Blog