Johnson Controls Metasys

August 13, 2026·Source: CISA

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TL;DR

View CSAF Summary Successful exploitation of this vulnerability could allow a low-privilege user or attacker to inject a persistent malicious payload via a crafted URL that executes in the context of other users' sessions, including administrators, potentially leading to session hijacking and unauthorized access. The following versions of Johnson Controls Metasys are affected: Metasys 12 vers:all/* (CVE-2026-34491) Metasys 13 vers:all/* (CVE-2026-34491) Metasys 14 Metasys 15 CVSS Vendor Equipment Vulnerabilities

v3 8 Johnson Controls Inc Johnson Controls Metasys Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

Background Critical Infrastructure Sectors: Critical Manufacturing, Commercial Facilities, Government Services and Facilities, Transportation Systems, Energy Countries/Areas Deployed: Worldwide Company Headquarters Location: Ireland Vulnerabilities Expand All + CVE-2026-34491 A low-privilege user can inject a malicious XSS payload into the Metasys UI via a crafted URL. The payload persists across logins and executes in the browser context of other users, including administrators. View CVE Details Affected Products Johnson Controls Metasys Vendor: Johnson Controls Inc Product Version: Johnson Controls Inc Metasys 12: vers:all/, Johnson Controls Inc Metasys 13: vers:all/, Johnson Controls Inc Metasys 14: <v14.1.5, Johnson Controls Inc Metasys 15: <v15.0.1 Product Status: known_affected Remediations Mitigation Johnson Controls recommends the following actions: Mitigation User are recommended to apply the latest available patches for affected Metasys versions Mitigation Metasys 16.0: Not impacted, fixed prior to release Vendor fix Metasys 15.0: Patch released 2026-03-25 Vendor fix Metasys 14.1.5: Forecast release 2026-07-15 Vendor fix Metasys 13: End of support, update to later version Vendor fix Metasys 12: End of support, update to later version Mitigation Metasys 11 & prior: Not affected (vulnerability introduced at

What Happened

Johnson Controls Metasys, reported by CISA.

v3 8 Johnson Controls Inc Johnson Controls Metasys Improper Neutralization of Input During Web Page Generation ('Cross-site Scripting')

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.

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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?

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