Medium severity · published Aug 24, 2026
CVE-2026-34491
Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Johnson Controls Metasys 14 and Johnson Controls Metasys 15 allows Cross Site…
6.1
CVSS
0.4%
EPSS
No
On KEV
Description
Improper neutralization of input during web page generation ('cross-site scripting') vulnerability in Johnson Controls Metasys 14 and Johnson Controls Metasys 15 allows Cross Site Scripting.
This issue affects Metasys 14: before 14.1.5; Metasys 15: before 15.0.1.
Exploitation
Is it being used?
Exploit prediction (EPSS)0.4% · higher than 34% of CVEs
Exploited in the wildNo evidence yet
CISA KEVNot listed
Ransomware campaign useNot known
Affected products
Which versions
M1
Metasys 14 · Johnson Controls
before 14.1.5 · source: vendor
M1
Metasys 15 · Johnson Controls
before 15.0.1 · source: vendor
In the news
VulnerabilityHigh
Johnson Controls Metasys
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,...
Aug 13, 2026·CISA Advisories
