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FM Systems Employee CVE-2026-34497

| EUVDEUVD-2026-51590 MEDIUM
Basic XSS (CWE-80)
2026-07-31 jci GHSA-9hxq-5m48-2w2f
4.8
CVSS 4.0 · Vendor: jci
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Attack ChainAIDerived

Hypothetical attack flow derived from CVE metadata – not a confirmed exploit chain

  1. Access
    Attacker obtains high-privilege FM Systems account
  2. Delivery
    Inject malicious script tag into application content field
  3. Exploit
    Victim user loads affected page
  4. Execution
    Browser executes injected script
  5. Impact
    Session token exfiltrated to attacker

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization HTML tag escaping
MITRE ATT&CK

1 technique across 1 tactic: Initial Access

The technique list with ATT&CK links and the kill-chain view is part of the Basic plan and up.

Exploitation Conditions

Exploitation requires two distinct conditions: first, the attacker must be authenticated with high-privilege access (PR:H per CVSS 4.0 vector) to the FM Systems Employee web application, meaning a compromised or malicious high-privileged account is a hard prerequisite. Second, a separate victim user must passively view the page containing the injected script (UI:P). Exploitation is limited to the web application context - it does not extend to subsequent systems (SC:N/SI:N/SA:N). The vulnerability affects only versions of FM Systems Employee before 2025.3.1. There is no indication from the available data that exploitation is possible in a default unauthenticated posture or without the high-privilege prerequisite.

Impact

The CVSS 4.0 vector AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N encodes the key risk limiters: exploitation requires an attacker who already holds high privileges (PR:H), and a victim who passively views the injected content (UI:P). Confidentiality impact is low (VC:L), with no integrity or availability impact claimed. This profile is consistent with a stored XSS where an admin-level user embeds a script that harvests another user's session credentials. Real-world risk is constrained: an attacker must first obtain high-privilege access to the FM Systems Employee application before the XSS becomes exploitable, significantly narrowing the threat population. There is no CISA KEV listing and no public exploit code identified, and EPSS data is not provided. The combination of high prerequisite privilege, low impact ceiling, and absence of known exploitation makes this a medium-to-low operational priority for most organizations, though patching remains appropriate. No conflicting signals between the description and the CVSS vector were identified.

Exploit ScenarioDerived

An attacker who has obtained high-privileged credentials to FM Systems Employee - whether through phishing, credential reuse, or insider access - navigates to a content input area and submits a payload containing a script tag designed to exfiltrate session cookies to an attacker-controlled endpoint. A second user with a valid session subsequently loads the page containing the injected content, causing their browser to execute the script and transmit their session token to the attacker. No public exploit code has been identified, so exploitation requires manual crafting of the payload.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.4% exploitation probability (EPSS)

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AnalysisAIv1 – Jul 31, 2026

Stored or reflected cross-site scripting in Johnson Controls FM Systems Employee (versions before 2025.3.1) allows a high-privileged authenticated attacker to inject script-related HTML tags into web pages that are subsequently rendered in other users' browsers. The attack requires passive user interaction from a victim and yields low-confidentiality impact, consistent with session token or cookie theft scoped to the vulnerable application. No public exploit code and no CISA KEV listing have been identified at time of analysis; CVSS 4.0 score of 4.8 reflects the constrained, privilege-gated nature of the vulnerability.

RemediationAI

Upgrade FM Systems Employee to version 2025.3.1 or later, which resolves this XSS vulnerability per the vendor advisory at https://www.johnsoncontrols.com/trust-center/cybersecurity/security-advisories. If immediate patching is not feasible, restrict access to the FM Systems Employee web interface to trusted internal networks and enforce least-privilege account management to limit the population of users who can inject content - since exploitation requires PR:H, reducing the number of high-privileged accounts directly limits attack surface. Implementing a Content Security Policy (CSP) header on the application server as a compensating control would reduce the impact of any injected scripts by blocking inline script execution, though this may affect legitimate application functionality and should be tested before deployment.

Affected VersionsENISA

FM Systems Employee 0 <2025.3.1

Affected Packages

euvd fm_systems_employee fix: 2025.3.1

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 1 package in euvd

Checking this CVE against your own stacks and servers is part of the Basic plan and up.

Technical ContextAI · show details

CWE-80 (Improper Neutralization of Script-Related HTML Tags) describes a failure to sanitize or encode user-supplied input before it is written into HTML output, enabling injection of tags such as <script>, <img onerror=...>, or similar constructs. The affected product is identified by CPE cpe:2.3:a:johnson_controls:fm_systems_employee:*:*:*:*:*:*:*:*, meaning all versions of Johnson Controls FM Systems Employee prior to 2025.3.1 are in scope. FM Systems Employee is a workplace and facility management web application. The XSS surface is within the web interface where high-privileged users can submit content that is later rendered to other users without adequate output encoding.

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Severity by source

Vendor (jci) PRIMARY 4.8 MEDIUM
CVSS:4.0/AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:N/VA:N/SC:N/SI:N/SA:N
vuln.today AI 4.8 MEDIUM

Network vector, high privileges required to inject; user interaction required for victim; scope changes to victim browser; low C and I for session/content impact.

3.1 AV:N/AC:L/PR:H/UI:R/S:C/C:L/I:L/A:N
4.0 AV:N/AC:L/AT:N/PR:H/UI:P/VC:L/VI:L/VA:N/SC:N/SI:N/SA:N

Primary rating from Vendor (jci).

CVSS VectorVendor: jci

Attack Vector
Network
Attack Complexity
Low
Attack Requirements
None
Privileges Required
High
User Interaction
Passive
Vulnerable system: Confidentiality
Low
Vulnerable system: Integrity
None
Vulnerable system: Availability
None
Subsequent system: Confidentiality
None
Subsequent system: Integrity
None
Subsequent system: Availability
None

Lifecycle Timeline

1
Patch available
Jul 31, 2026 - 19:02 EUVD

DescriptionCVE.org

Improper neutralization of Script-Related HTML tags in a web page (basic XSS) vulnerability in Johnson Controls FM Systems Employee allows Cross-Site Scripting (XSS).

This issue affects FM Systems Employee: before 2025.3.1.

Threat Intelligence Overview

EPSS Score
0.4%
Top 66% exploitable
Prevalence
Low
niche enterprise facility management product, limited deployment footprint
Threat Intel
1
1 source
Data Quality
7 sources
Confidence: High
EUVD NVD CVE.org EPSS Vulnrichment CISA VulDB

How this decision was reached

The engine reads each signal below and applies a fixed list of rules from top to bottom. The first rule that matches sets the recommended action – like a statement, every line is shown.

SignalValue
Severity MEDIUM
CISA KEV No
Public POC No
EPSS 0.4%
Patch available Yes
Active threat Yes
Deciding rule
MEDIUM severity (CVSS 4.0-6.9)
What every action level means
Emergency Immediate action required. Criteria: CRITICAL + in CISA KEV (actively exploited) without patch, OR CRITICAL + EPSS > 30% without patch, OR CRITICAL + active threat signals without patch.
Act Now Prioritize within 24-48h. Criteria: in KEV with patch available, OR CRITICAL + public POC, OR HIGH + EPSS > 10%, OR CRITICAL + active threat, OR any CRITICAL severity.
This Week Schedule remediation this week. Criteria: HIGH severity (CVSS 7.0-8.9). Patch within normal change window.
This Month Plan within 30 days. Criteria: MEDIUM severity (CVSS 4.0-6.9), lower exploitation probability. Include in regular patch cycle.
Monitor Track and reassess. Criteria: LOW severity (CVSS 0.1-3.9), minimal exploitation risk. No immediate action needed.

SSVC AssessmentENISA

SSVC Decision· derived
Scheduled
Exploitation
None
System Exposure· derived
Open
Automatable
No
Human Impact· derived
Medium
Technical Impact
Partial

Priority Score

34
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: +10
Gov advisory: 0

Attack Technique

Cross-Site Scripting occurs when an application accepts untrusted data and sends it to a web browser without proper validation or encoding.

Threat IntelligenceMISP

CISA Advisories
Sources: CISA (public domain)

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