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Vulnerability record · CVE-2019-6553 · published 4 April 2019

CVE-2019-6553: Rockwell RSLinx Classic stack buffer overflow via Forward Open request

Rockwellautomation · Rslinx

Rockwell Automation RSLinx Classic 4.10.00 and prior contains an input validation flaw in a DLL where data from a Forward Open service request is copied into a fixed-size buffer, causing a stack-based buffer overflow. Because RSLinx Classic is commonly used on engineering workstations to bridge industrial devices, a memory-corruption bug here can compromise the host that talks to control systems.

9.8 CVSS 3.1 Critical EPSS 66% · top 0.7% CWE-121 · Stack-based buffer overflowCWE-787 · Out-of-bounds write
9.8CVSS 3.1 base score, v2 7.5
66%EPSS exploitation probability, 30 days
NoNot in CISA KEV
1Affected product versions listed by NVD
2References
17 Jun 2026Last modified by NVD

Description

A vulnerability was found in Rockwell Automation RSLinx Classic versions 4.10.00 and prior. An input validation issue in a .dll file of RSLinx Classic where the data in a Forward Open service request is passed to a fixed size buffer, allowing an attacker to exploit a stack-based buffer overflow condition.

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H

Automated analysis

Generated by VULONE's analysis model from the NVD record, CISA KEV and EPSS data on 19 September 2026. Confidence: medium.

critical priorityCVSS 9.8 with network reachability, no authentication and no user interaction, combined with a very high EPSS score, makes this a high-impact remotely triggerable flaw despite no KEV listing.

What it is

Rockwell Automation RSLinx Classic 4.10.00 and prior contains an input validation flaw in a DLL where data from a Forward Open service request is copied into a fixed-size buffer, causing a stack-based buffer overflow. Because RSLinx Classic is commonly used on engineering workstations to bridge industrial devices, a memory-corruption bug here can compromise the host that talks to control systems.

Impact

An unauthenticated remote attacker can corrupt the stack and potentially execute arbitrary code with the privileges of the RSLinx process, giving full control of the affected workstation.

Attack surface

The CVSS vector is network-reachable with no privileges and no user interaction (AV:N/AC:L/PR:N/UI:N), and the flaw is triggered by a crafted Forward Open service request, so it is reached over the network via the industrial protocol rather than through local access.

Exploitation

Not listed in CISA KEV and no ransomware associations are documented, but EPSS is high at roughly 0.60 probability (99th percentile), indicating elevated likelihood of attempted exploitation; the only references are US-CERT/ICS-CERT advisories with no public exploit tag.

What to do

  • Upgrade RSLinx Classic to a version later than 4.10.00 per the Rockwell/ICS-CERT advisory ICSA-19-064-01.
  • If upgrade is not immediately possible, restrict network access to RSLinx hosts using firewalls and segmentation so only trusted engineering systems can reach the relevant services.
  • Disable or block unnecessary industrial protocol services and ports on RSLinx workstations.
  • Apply vendor-recommended hardening and monitor Rockwell advisories for updated guidance.
  • Limit interactive use of RSLinx workstations to trusted personnel and remove unnecessary software.

Detection

  • Monitor network traffic for malformed or unexpected Forward Open service requests directed at RSLinx hosts.
  • Watch for crashes or abnormal termination of RSLinx Classic processes and associated DLLs on engineering workstations.
  • Alert on unexpected outbound connections or new processes spawned by RSLinx on OT hosts.
  • Review host logs for memory-corruption indicators such as access violations in RSLinx-related modules.

This assessment is produced automatically and is not human-reviewed. Verify against the vendor advisory before acting on it.

Affected products

1 vulnerable configurations from NVD's CPE data, grouped by vendor and product.

References

LinkTags
https://ics-cert.us-cert.gov/advisories/ICSA-19-064-01 Third Party AdvisoryUS Government Resource
https://ics-cert.us-cert.gov/advisories/ICSA-19-064-01 Third Party AdvisoryUS Government Resource

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Related vulnerabilities

Same products first, then exploited flaws of the same weakness class.

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Source: NIST National Vulnerability Database (record CVE-2019-6553), CISA KEV, FIRST EPSS (scores of 2026-09-27). This page is refreshed as NVD updates the record.