OpenPLC Runtime v3
OpenPLC Runtime v3 XSS can hijack operator sessions and control PLC processes.
CISA published an ICS advisory for CVE-2026-88020, a cross-site scripting flaw in Autonomy Logic OpenPLC Runtime v3. The web interface uses an unencoded query-string parameter when routing programs, which can let an attacker hijack session cookies and issue operator requests. That access could control the programmable logic controller and the physical processes it drives. CVSS 3.1 is 6.1 and CVSS 4.0 is 5.3. OpenPLC 3 is affected, and CISA says no known public exploitation has been reported.
- CVE-2026-88020 is cross-site scripting in OpenPLC Runtime version 3.
- Unencoded query parameters can lead to operator session hijacking.
- A hijacked operator could control the PLC and physical processes.
- CISA reports no known public exploitation of this flaw.
Vulnerabilities mentionedAll →
- CVE-2026-880205.3—Reflected XSS in Autonomy Logic OpenPLC 3 Web Interfacepublished · Autonomy Logic OpenPLC Runtime
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2026-88020 | Reflected XSS in Autonomy Logic OpenPLC 3 Web Interface OpenPLC 3, an open-source programmable logic controller (PLC) runtime from Autonomy Logic, contains a cross-site scripting flaw (CWE-79) in its web interface: when the interface routes a program based on a query string parameter, the parameter is used without encoding or neutralization. An attacker can craft a malicious link that, when clicked by a user interacting with the OpenPLC web console, executes attacker-controlled script in the victim's browser in the context of the PLC's web application. Because that console manages control programs and physical I/O, a successful attack could allow session hijacking or unauthorized actions with the victim's privileges, such as viewing or manipulating control logic. The flaw is rated medium (CVSS 4.0: 5.3) and requires no privileges but does require user interaction, typical of reflected XSS. No public proof-of-concept exists and the vulnerability is not listed in CISA's Known Exploited Vulnerabilities catalog. |
Full article520 words · extracted from cisa.gov · click to collapse
Summary
Successful exploitation of this vulnerability could allow an attacker to hijack session cookies and issue state-changing requests as an operator which would allow the attacker to control the programmable logic controller and the physical processes it drives.
The following versions of OpenPLC Runtime v3 are affected:
- OpenPLC 3 (CVE-2026-88020)
| CVSS | Vendor | Equipment | Vulnerabilities |
|---|---|---|---|
| v3 6.1 | Autonomy Logic | OpenPLC Runtime v3 | Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting') |
Background
- Critical Infrastructure Sectors: Critical Manufacturing, Energy, Transportation Systems, Water and Wastewater Systems
- Countries/Areas Deployed: Worldwide
- Company Headquarters Location: United States
Vulnerabilities
CVE-2026-88020
The affected product is susceptible to an improper neutralization of input during web page generation vulnerability when the web interface attempts to route the program based on a query string parameter with no encoding.
Affected Products
OpenPLC Runtime v3
Vendor:
Autonomy Logic
Product Version:
Autonomy Logic OpenPLC: 3
Product Status:
known_affected
Relevant CWE: CWE-79 Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')
Metrics
| CVSS Version | Base Score | Base Severity | Vector String |
|---|---|---|---|
| 3.1 | 6.1 | MEDIUM | CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N |
| 4.0 | 5.3 | MEDIUM | CVSS:4.0/AV:N/AC:L/AT:N/PR:N/UI:P/VC:L/VI:L/VA:N/SC:L/SI:L/SA:N |
Acknowledgments
- Rajivarnan R. and Shirshak of Secnora reported this vulnerability to CISA.
Legal Notice and Terms of Use
This product is provided subject to this Notification (https://www.cisa.gov/notification) and this Privacy & Use policy (https://www.cisa.gov/privacy-policy).
Recommended Practices
CISA recommends users take defensive measures to minimize the risk of exploitation of this vulnerability.
- Minimize network exposure for all control system devices and/or systems, ensuring they are not accessible from the internet.
- Locate control system networks and remote devices behind firewalls and isolating them from business networks.
- When remote access is required, use more secure methods, such as Virtual Private Networks (VPNs), recognizing VPNs may have vulnerabilities and should be updated to the most current version available. Also recognize VPN is only as secure as the connected devices.
CISA reminds organizations to perform proper impact analysis and risk assessment prior to deploying defensive measures.
CISA also provides a section for control systems security recommended practices on the ICS webpage on cisa.gov/ics. Several CISA products detailing cyber defense best practices are available for reading and download, including Improving Industrial Control Systems Cybersecurity with Defense-in-Depth Strategies.
CISA encourages organizations to implement recommended cybersecurity strategies for proactive defense of ICS assets.
Additional mitigation guidance and recommended practices are publicly available on the ICS webpage at cisa.gov/ics in the technical information paper, ICS-TIP-12-146-01B--Targeted Cyber Intrusion Detection and Mitigation Strategies.
Organizations observing suspected malicious activity should follow established internal procedures and report findings to CISA for tracking and correlation against other incidents.
CISA also recommends users take the following measures to protect themselves from social engineering attacks:
- Do not click web links or open attachments in unsolicited email messages.
- Refer to Recognizing and Avoiding Email Scams for more information on avoiding email scams.
- Refer to Avoiding Social Engineering and Phishing Attacks for more information on social engineering attacks.
No known public exploitation specifically targeting this vulnerability has been reported to CISA at this time.
Revision History
- Initial Release Date: 2026-09-22
| Date | Revision | Summary |
|---|---|---|
| 2026-09-22 | 1 | Initial Publication |