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Nozomi Guardian EUVDEUVD-2025-209896

| CVE-2025-40903 MEDIUM
Cross-site Scripting (XSS) (CWE-79)
2026-05-19 Nozomi GHSA-9pfj-vxgx-63wq
4.8
CVSS 4.0 · Vendor: Nozomi
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Attack ChainAIDerived

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

  1. Recon
    Obtain administrative credentials
  2. Delivery
    Authenticate to Guardian or CMC
  3. Exploit
    Inject HTML payload into Schedule Restore Archive parameter
  4. Install
    Payload persists server-side
  5. C2
    Victim user views affected schedule
  6. Execute
    Browser renders injected HTML
  7. Impact
    Victim redirected to phishing site

Vulnerability Assessment

Weakness
CWE
OWASP Top 10:2025
A05:2025 - Injection
ASVS 5.0
V1 - Encoding and Sanitization Output encoding, context-aware escaping
MITRE ATT&CK

2 techniques across 2 tactics: Initial Access, Execution

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

Exploitation Conditions

Exploitation requires an authenticated session with high (administrative) privileges on Nozomi Networks Guardian or CMC, as confirmed by PR:H in the CVSS 4.0 vector - an attacker must have already obtained administrative credentials before injecting content. A second condition is victim interaction: a separate user must navigate to and view the affected Schedule Restore Archive entry in their browser (UI:P per CVSS). The injection point is specifically the Schedule Restore Archive input parameter; other configuration areas are not implicated by this CVE. Full XSS execution is not achievable due to active Content Security Policy enforcement and server-side input validation, as explicitly confirmed in the CVE description - attack outcomes are limited to HTML rendering effects such as phishing anchors and open redirects. Non-administrative users cannot trigger the injection phase, and users who never view the affected schedule entry are not exposed.

Impact

The CVSS 4.0 score of 4.8 (Medium) accurately reflects a meaningfully constrained attack profile: while the attack vector is network-accessible (AV:N) with no additional complexity (AC:L), exploitation demands high privileges (PR:H - administrative account) and passive victim interaction (UI:P - a user must view the schedule). These two prerequisites together substantially reduce real-world risk. No EPSS score was provided in the source data, so exploitation probability cannot be quantified from that signal. The vulnerability is not listed in the CISA KEV catalog, and no public proof-of-concept has been identified, indicating no confirmed active or widespread exploitation at time of analysis. Impact scores across all dimensions are rated Low (VC:L/VI:L/VA:L/SC:L/SI:L/SA:L), consistent with the description's confirmation that direct information disclosure and full XSS are prevented by existing controls. For most enterprise environments this represents a low-urgency patching candidate; however, in OT/ICS contexts, administrative account compromise followed by operator-targeted phishing carries disproportionate risk given the sensitivity of the underlying systems being managed.

Exploit ScenarioDerived

An attacker who has obtained valid administrative credentials for a Nozomi Networks Guardian or CMC instance navigates to the Schedule Restore Archive feature and creates or modifies a restore schedule, embedding HTML such as a hidden anchor tag pointing to a credential-harvesting site or a meta refresh open redirect into the vulnerable input parameter. When a network operator or security analyst subsequently opens the schedule view in their browser, the injected HTML renders, potentially presenting a convincing phishing link disguised within the legitimate management interface. No public proof-of-concept is known; full JavaScript execution via this vector is prevented by the platform's Content Security Policy.

This Month Plan within 30 days. Why: MEDIUM severity (CVSS 4.0-6.9).
Patch available 0.0% exploitation probability (EPSS)

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AnalysisAIv1 – May 19, 2026

Stored HTML injection in Nozomi Networks Guardian and CMC's Schedule Restore Archive feature permits authenticated administrators to embed arbitrary HTML tags within restore schedule configurations. When any user views the poisoned schedule entry, the injected markup renders in their browser, enabling phishing lures and potential open redirect attacks against operators. Full JavaScript execution is blocked by the platform's existing Content Security Policy and server-side validation, and no public exploit has been identified at time of analysis; however, in OT/ICS environments where operator trust is high, even HTML-level injection can support targeted social engineering.

RemediationAI

Upgrade Nozomi Networks Guardian and CMC to version 26.1.0 or later, which remediates the improper input validation in the Schedule Restore Archive functionality. The authoritative vendor advisory with upgrade guidance is available at https://security.nozominetworks.com/NN-2026:6-01. As an interim compensating control prior to patching, restrict administrative access to the minimum number of trusted personnel using role-based access controls, reducing the likelihood that a compromised admin account can inject content - note this does not eliminate the vulnerability but raises the bar for exploitation. Additionally, audit existing restore schedule configurations for unexpected HTML tags (anchor elements, iframes, meta refresh directives) to identify any prior injection attempts. Enabling alerting on administrative configuration changes in the schedule restore area can provide detection coverage while patches are applied.

Affected VersionsENISA

Guardian 0 <26.1.0
CMC 0 <26.1.0

Affected Packages

euvd cmc fix: 26.1.0
euvd guardian fix: 26.1.0

Source: OSV (Open Source Vulnerabilities)

Affects your stack

Affects 2 packages in euvd

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

Technical ContextAI · show details

Nozomi Networks Guardian and CMC (Central Management Console) are OT/IoT network visibility and security monitoring platforms widely deployed in critical infrastructure environments. The vulnerability resides in the Schedule Restore Archive feature, where a specific input parameter is insufficiently sanitized before being persisted and later rendered in the browser. CWE-79 (Improper Neutralization of Input During Web Page Generation) identifies the root cause as a failure to neutralize user-controlled content prior to HTML rendering - a stored variant, meaning the payload persists server-side and executes for any subsequent viewer without further attacker interaction. CPE strings cpe:2.3:a:nozomi_networks:guardian:*:*:*:*:*:*:*:* and cpe:2.3:a:nozomi_networks:cmc:*:*:*:*:*:*:*:* confirm both product lines are affected across all versions prior to 26.1.0. Existing Content Security Policy headers prevent escalation to full script execution, confining the practical attack surface to HTML-level effects such as anchor tag injection, iframe embedding, and open redirect payloads.

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Severity by source

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

Primary rating from Vendor (Nozomi) · only source for this CVE.

CVSS VectorVendor: Nozomi

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

Lifecycle Timeline

2
CVSS changed
May 19, 2026 - 14:22 NVD
5.9 (MEDIUM) 4.8 (MEDIUM)
Patch available
May 19, 2026 - 14:02 EUVD

DescriptionCVE.org

A Stored HTML Injection vulnerability was discovered in the Schedule Restore Archive functionality due to improper validation of an input parameter. An authenticated user with administrative privileges can define a malicious restore schedule containing HTML tags. When a victim views the affected schedule, the injected HTML renders in their browser, enabling phishing and possibly open redirect attacks. Full XSS exploitation and direct information disclosure are prevented by the existing input validation and Content Security Policy configuration.

Threat Intelligence Overview

EPSS Score
0.0%
Top 92% exploitable
Data Quality
5 sources
Confidence: Medium

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 0.0%
Patch available Yes
Active threat No
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

24
Low Medium High Critical
KEV: 0
EPSS: 0
CVSS: +24
PoC: 0
Weaponized: 0
Threat intel: 0
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.

Information disclosure occurs when an application unintentionally exposes sensitive data that aids attackers in reconnaissance or directly compromises security.

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